Because vs. Because of – English Grammar Exercises for B1
Writing a professional email to a manager to request a sick day due to health issues.
Choose the best option (A, B, C, or D) to complete each sentence. Read the context carefully. Pay close attention to the words immediately following the blank to decide whether you need a conjunction for a full clause (Subject + Verb) or a preposition for a noun phrase indicating an illness.
1 Dear Manager, I am writing to inform you that I cannot come to the office today ________ a severe migraine.
(A) because
(B) because of
(C) because off
(D) despite
2 I need to take a sick leave today ________ I woke up with a high fever this morning.
(A) because of
(B) so
(C) due to
(D) because
3 Please excuse my sudden absence today ________ my terrible food poisoning.
(A) because of
(B) reason of
(C) because
(D) nevertheless
4 I will not be able to attend the 9 AM meeting ________ I am currently waiting at the doctor’s clinic.
(A) because that
(B) therefore
(C) because
(D) because of
5 I am requesting to work from home today ________ a mild case of the flu.
(A) because
(B) because of
(C) owing
(D) because from
6 I am taking the rest of the day off ________ my doctor strongly advised me to rest completely.
(A) due to
(B) because of
(C) because
(D) because it
7 I won’t be able to log in to the company system today ________ an unexpected medical emergency.
(A) because
(B) though
(C) because for
(D) because of
8 I will hand over my urgent tasks to Sarah ________ I need to go to the hospital right now.
(A) because
(B) because of
(C) so that
(D) because with
9 I sincerely apologize for the late notice, but I cannot come in ________ a stomach bug.
(A) due of
(B) because of
(C) because
(D) because to
10 I am unable to lead the presentation this afternoon ________ my severely sore throat.
(A) regardless of
(B) because
(C) reason of
(D) because of
11 I have to request a two-day medical leave ________ my doctor needs to run some blood tests.
(A) because of
(B) in spite of
(C) because
(D) for because
12 Please delay the project review until tomorrow ________ my current health condition.
(A) because of
(B) because
(C) instead of
(D) because by
13 I am writing to ask for a sick day ________ I caught a terrible cold during the weekend trip.
(A) due to
(B) because
(C) because having
(D) because of
14 I won’t be online to answer emails this afternoon ________ a scheduled dental surgery.
(A) because
(B) nevertheless
(C) because of
(D) cause
15 I am attaching my medical certificate to this email ________ HR needs it for the attendance record.
(A) because of
(B) regardless of
(C) because for
(D) because
16 I need to log off early today ________ this strong medication making me extremely dizzy.
(A) because off
(B) because of
(C) however
(D) because
17 I am unable to join the conference call ________ my internet connection is unstable, and I feel very unwell.
(A) because
(B) because of
(C) as a result
(D) because that
18 I will miss the team lunch today ________ a severe allergic reaction I had last night.
(A) since of
(B) despite
(C) because of
(D) because
19 I am taking some time to recover ________ I want to be fully productive when I return tomorrow.
(A) consequently
(B) because
(C) because of
(D) because am
20 I have set up an auto-reply on my email ________ the fact that I will be away from my desk all day.
(A) because
(B) reason
(C) although
(D) because of
ANSWER KEY & EXPLANATIONS
1 (B)
- Why it is correct (The Key): “A severe migraine” is a noun phrase. Therefore, we must use the preposition “because of” to indicate the reason. This makes the email sound formal and concise.
- Error Analysis: (A) “Because” must be followed by a full clause (Subject + Verb) (Common Mistake). (C) Incorrect spelling (Structural Error). (D) “Despite” contradicts the logic of the sentence (Meaning Trap).
2 (D)
- Why it is correct (The Key): “I woke up with a high fever” is a full independent clause (Subject = I, Verb = woke up). We must use the conjunction “because”.
- Error Analysis: (A) “Because of” cannot be followed by a full clause (Common Mistake). (B) “So” indicates a result, not a reason (Meaning Trap). (C) “Due to” is a preposition requiring a noun phrase (Common Mistake).
3 (A)
- Why it is correct (The Key): “My terrible food poisoning” is a noun phrase acting as the direct cause. We use “because of”.
- Error Analysis: (B) “Reason of” is not a standard grammatical connector here (Structural Error). (C) “Because” requires a subject and a verb (Common Mistake). (D) “Nevertheless” introduces contrast, which is illogical (Meaning Trap).
4 (C)
- Why it is correct (The Key): “I am currently waiting at the doctor’s clinic” is a full clause. It requires “because”.
- Error Analysis: (A) “Because that” is a grammatical error (Structural Error). (B) “Therefore” shows a result, not a cause (Meaning Trap). (D) “Because of” cannot precede a full clause (Common Mistake).
5 (B)
- Why it is correct (The Key): “A mild case of the flu” is a noun phrase. We need “because of”.
- Error Analysis: (A) “Because” requires a clause (Common Mistake). (C) “Owing” must be followed by “to” (Structural Error). (D) “Because from” is structurally invalid (Structural Error).
6 (C)
- Why it is correct (The Key): “My doctor strongly advised me…” is a complete clause (Subject = my doctor, Verb = advised). We use “because”.
- Error Analysis: (A) “Due to” is a preposition (Meaning Trap). (B) “Because of” cannot precede a clause (Common Mistake). (D) “Because it” creates a double subject (Structural Error).
7 (D)
- Why it is correct (The Key): “An unexpected medical emergency” is a noun phrase. We use “because of”.
- Error Analysis: (A) “Because” needs a conjugated verb (Common Mistake). (B) “Though” means “although,” which is illogical (Meaning Trap). (C) “Because for” is invalid (Structural Error).
8 (A)
- Why it is correct (The Key): “I need to go to the hospital” is a full clause. We use “because”.
- Error Analysis: (B) “Because of” cannot be followed by a clause (Common Mistake). (C) “So that” indicates purpose, not reason (Meaning Trap). (D) “Because with” is structurally wrong (Structural Error).
9 (B)
- Why it is correct (The Key): “A stomach bug” is a short, formal noun phrase. We use “because of”.
- Error Analysis: (A) “Due of” is an invalid mix of “due to” and “because of” (Structural Error). (C) “Because” needs a full clause (Common Mistake). (D) “Because to” is invalid (Structural Error).
10 (D)
- Why it is correct (The Key): “My severely sore throat” is a noun phrase. We use “because of”.
- Error Analysis: (A) “Regardless of” means “despite”, changing the logic completely (Meaning Trap). (B) “Because” needs a full clause (Common Mistake). (C) “Reason of” is structurally incorrect (Structural Error).
11 (C)
- Why it is correct (The Key): “My doctor needs to run some blood tests” is a full clause. “Because” is the correct conjunction.
- Error Analysis: (A) “Because of” is used before nouns, not clauses (Common Mistake). (B) “In spite of” gives an opposite meaning (Meaning Trap). (D) “For because” is redundant and invalid (Structural Error).
12 (A)
- Why it is correct (The Key): “My current health condition” is a noun phrase. We use “because of”.
- Error Analysis: (B) “Because” needs a subject and a verb (Common Mistake). (C) “Instead of” means replacing something, making no sense here (Meaning Trap). (D) “Because by” is a broken structure (Structural Error).
13 (B)
- Why it is correct (The Key): “I caught a terrible cold” is a full clause. We use “because”.
- Error Analysis: (A) “Due to” cannot precede a full clause (Meaning Trap). (C) “Because having” is grammatically invalid (Structural Error). (D) “Because of” is for noun phrases only (Common Mistake).
14 (C)
- Why it is correct (The Key): “A scheduled dental surgery” is a noun phrase. We need “because of”.
- Error Analysis: (A) “Because” requires a main verb (Common Mistake). (B) “Nevertheless” is illogical (Meaning Trap). (D) “Cause” as a standalone preposition is overly informal for a corporate email (Structural Error).
15 (D)
- Why it is correct (The Key): “HR needs it for the attendance record” is a full clause. We use “because”.
- Error Analysis: (A) “Because of” is for noun phrases (Common Mistake). (B) “Regardless of” breaks the logic (Meaning Trap). (C) “Because for” is invalid (Structural Error).
16 (B)
- Why it is correct (The Key): “This strong medication making me extremely dizzy” is a noun phrase. “Making” is a participle modifying the medication, not the main conjugated verb of a clause. We use “because of”.
- Error Analysis: (A) “Because off” is a spelling error (Structural Error). (C) “However” is an adverb of contrast (Meaning Trap). (D) “Because” requires a main conjugated verb, which is absent here (Common Mistake).
17 (A)
- Why it is correct (The Key): “My internet connection is unstable” is a full clause. We use “because”.
- Error Analysis: (B) “Because of” cannot take a full clause (Common Mistake). (C) “As a result” points to an effect, not a cause (Meaning Trap). (D) “Because that” is a structural error (Structural Error).
18 (C)
- Why it is correct (The Key): “A severe allergic reaction” is a noun phrase (even though a relative clause “I had last night” modifies it, the core is still a noun). We use “because of”.
- Error Analysis: (A) “Since of” is invalid (Structural Error). (B) “Despite” breaks the logic (Meaning Trap). (D) “Because” needs to directly introduce a full independent clause, not a noun phrase (Common Mistake).
19 (B)
- Why it is correct (The Key): “I want to be fully productive…” is a full clause. We use “because”.
- Error Analysis: (A) “Consequently” (Meaning Trap). (C) “Because of” cannot take a clause (Common Mistake). (D) “Because am” is missing the subject “I” (Structural Error).
20 (D)
- Why it is correct (The Key): “The fact that” acts as a noun phrase block. We must use “because of” right before “the fact”.
- Error Analysis: (A) “Because” cannot immediately precede “the fact that” (Common Mistake). (B) “Reason” needs proper prepositional formatting (Structural Error). (C) “Although” breaks the cause/effect logic (Meaning Trap).
GRAMMAR POINTS TO REMEMBER
- Professional Conciseness (Because of + Illness):
- In formal emails, writing “because of a severe headache” or “because of a medical emergency” sounds highly professional and to the point. It is often preferred over writing long sentences like “because I have a severe headache.”
- Rule: Always use Because of when the reason is a Noun or a Noun Phrase.
- BECAUSE + Clause (Subject + Verb):
- Use Because when you need to explain an action or situation using a full sentence. It MUST be followed by a Subject and a conjugated Verb.
- Example: I am taking a sick leave because [my doctor] [advised] me to rest.
- The “Participle” Trap:
- Be careful with sentences like: “I am logging off early ________ this medication making me dizzy.” * Many learners see the word “making” and think it is a Verb, so they choose “Because”. However, “making” is just a participle describing the medication. The core is still a Noun Phrase (“this medication”). Therefore, you must use Because of.