Students can practice selecting the correct auxiliary verb to complete sentences with this engaging worksheet.

Let’s go step by step through each sentence to pick the correct auxiliary verb.

Remember: Auxiliary verbs help show when something happened (past, present, future) and must match the subject in number and tense.

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1. The bus ______ running late today.

- “The bus” is singular → needs a singular auxiliary.
- “Running” is a present participle → we need “is” for present continuous.
- ✔ Correct: B. is

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2. I ______ sent the kids along their way.

- “I” is first person singular.
- “Sent” is past tense → we need an auxiliary that works with past perfect or simple past? Wait — actually, this looks like it’s trying to be present perfect (“have sent”) but let’s check options:
- A. are → doesn’t fit with “sent”
- B. do → “do sent” is wrong; should be “did send” if past
- C. have → “I have sent” = present perfect → grammatically correct!
- But wait — is “sent” being used as main verb? Yes. So “have sent” is correct for present perfect.
- However… look at context: “along their way” suggests completed action → present perfect fits.
- BUT — option B is “do”, which would require base form “send”, not “sent”. So only “have” works with “sent”.
- ✔ Correct: C. have

Wait — hold on! Let me double-check.

Actually, maybe the sentence is meant to be simple past? Then it would be “I sent...” — no auxiliary needed. But since we MUST choose one, and “have sent” is grammatical, while “do sent” is not, and “are sent” is passive (doesn’t make sense here), then yes — C. have is best.

But let’s think again — perhaps there’s a trick. Is “sent” being used correctly? Maybe the intended meaning is “I did send...” — but “did” isn’t even an option! Options are: are, do, have.

So among given choices, only “have” can pair with “sent” to make a correct verb phrase: “I have sent”.

✔ Still going with C. have

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3. The repairman ______ finally arrived.

- “Arrived” is past tense.
- We don’t usually use auxiliary with simple past unless emphasizing — e.g., “did arrive”.
- But “did” isn’t an option.
- Options: does, is, has
- “does arrived” → wrong (should be “does arrive”)
- “is arrived” → archaic/passive, not standard modern English
- “has arrived” → present perfect → very common and correct!
- “The repairman has finally arrived.” → sounds natural and correct.
- ✔ Correct: C. has

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4. I ______ believe it’s going to be a good day.

- “Believe” is present tense verb.
- Subject “I” → we might use “do” for emphasis: “I do believe...”
- “Are believe” → wrong
- “Have believe” → wrong (should be “have believed”)
- Only “do” makes sense here for emphasis or affirmation.
- Example: “I do believe you!” → correct usage.
- ✔ Correct: B. do

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5. This experiment ______ suggest some interesting ideas.

- “This experiment” = singular subject.
- “Suggest” is base form → so we need auxiliary that matches singular + base verb.
- “Does suggest” → correct for third person singular present tense emphasis.
- “Is suggest” → wrong
- “Has suggest” → wrong (should be “has suggested”)
- So “does” is correct: “This experiment does suggest...” → emphasizes that it really does suggest something.
- ✔ Correct: A. does

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6. None of the students ______ completed the application.

- “None of the students” → treated as plural in modern usage (though sometimes singular, but here likely plural).
- “Completed” is past participle → so we need “have” for present perfect.
- “None... have completed” → correct.
- “Do completed” → wrong
- “Are completed” → passive, doesn’t fit
- Also, “none” can take plural verb when referring to countable nouns (students).
- ✔ Correct: C. have

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7. My dog ______ recently become afraid of toys.

- “Become” is past participle → so we need “has” for present perfect.
- “My dog” = singular → “has become”
- “Does become” → would need base form, and doesn’t fit “recently”
- “Is become” → incorrect
- ✔ Correct: B. is? Wait — no!

Hold on — “become” is irregular: become → became → become (past participle same as base? No!)

Actually:
Base: become
Past: became
Past participle: become ← yes, same as base.

So: “has become” is correct.

Options:
A. does → “does become” = present simple, but “recently” suggests present perfect
B. is → “is become” = old-fashioned/poetic, not standard
C. has → “has become” = correct present perfect

✔ So answer is C. has

Wait — I think I made a mistake earlier labeling. Let me recheck:

Question 7 options:
A. does
B. is
C. has

Yes — “has become” is correct → C. has

But in my initial quick pass I said B — that was wrong. Correction: C. has

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8. When the sun ______ comes out, I will go out and play.

- “Comes out” is present simple → we don’t normally add auxiliary unless for emphasis.
- But let’s see options:
- A. does → “does comes” → WRONG! Should be “does come”
- B. is → “is comes” → wrong
- C. has → “has comes” → wrong

Wait — none seem right? That can’t be.

Perhaps the sentence is: “When the sun comes out...” — no auxiliary needed. But we must choose one.

Maybe it’s testing emphasis? Like: “When the sun DOES come out...” — but then it should be “come”, not “comes”.

Ah — here’s the issue: the verb is written as “comes”, which is third person singular present. If we use “does”, we must change to base form: “does come”.

But the sentence says “comes” — so adding “does” would create error.

Unless... is this a trick? Maybe the correct answer is that NO auxiliary is needed — but we have to pick from A, B, C.

Alternatively — perhaps “is” is being considered for future? No.

Wait — another thought: maybe “the sun” is subject, and “comes out” is verb — but perhaps they want “does” for emphasis, and we ignore the “s”? Unlikely.

Let me read carefully: “When the sun ______ comes out...”

If we put “does”, it becomes “does comes” — ungrammatical.

If we put “is”, “is comes” — worse.

If we put “has”, “has comes” — also wrong.

This seems flawed — but perhaps in context, they expect “does” assuming student knows to drop the ‘s’? But the word is printed as “comes”.

Wait — maybe I misread. Let me imagine the blank: “When the sun ___ comes out”

Actually — perhaps the verb is “come”, and “comes” is a typo? Or perhaps in some dialects?

No — better approach: in standard grammar, for emphasis in present simple with third person singular, we say: “He DOES come” — not “does comes”.

So if the sentence has “comes”, then none of the auxiliaries work — but since we must choose, and “does” is the only one that could possibly be used (if we mentally correct to “come”), maybe that’s what they want.

But that’s not fair.

Alternative idea: perhaps “is” is for future? Like “when the sun is coming out” — but it says “comes out”, not “coming out”.

I think there might be an error in the question — but looking at similar worksheets, often they test “does” for emphasis even if verb form is off — but that’s bad teaching.

Wait — let’s look back at question 8: “When the sun ______ comes out, I will go out and play.”

Perhaps the intended answer is that no auxiliary is needed — but since we have to choose, and “does” is the only one that can be used with present simple for emphasis (with corrected verb), maybe they expect A.

But strictly speaking, all are wrong.

However, in many such tests, they overlook the verb form and just want the auxiliary that matches the subject for emphasis.

“Sun” is singular → “does” for emphasis.

And perhaps “comes” is a mistake — should be “come”.

Given that, and since other questions are clear, I’ll go with A. does as the intended answer, assuming they meant “come”.

But let’s verify with logic: in spoken English, people might say “When the sun does come out...” — so if the worksheet has a typo, “does” is the only plausible choice.

✔ Final decision for #8: A. does

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Now let’s compile all answers:

1. B. is
2. C. have
3. C. has
4. B. do
5. A. does
6. C. have
7. C. has
8. A. does

Wait — for #2, I’m still unsure. Let me revisit:

2. I ______ sent the kids along their way.

If we use “have”, it’s “I have sent” — present perfect — which implies recent completion or relevance to now. That works.

But is there a possibility it’s simple past? Then no auxiliary — but we must choose.

Option B is “do” — “I do sent” is always wrong.

Option A “are” — “I are sent” — nonsense.

So only C works.

Similarly, for #7, “has become” is correct.

For #8, despite the verb form issue, “does” is the only auxiliary that could be used for emphasis with present simple, so we’ll go with that.

Final Answers:

1. B
2. C
3. C
4. B
5. A
6. C
7. C
8. A

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Final Answer:
1. B
2. C
3. C
4. B
5. A
6. C
7. C
8. A