`1.` We will be successful if we try hard, ____ we?

`⇒` `won't`

`⇒` Explain: In this case, when the statement is positive, we use a negative question tag. Since the auxiliary verb in this sentence is " will ", its negative form is " won't ".

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`2.` Dorothy must stop drinking, _______ she?

`⇒` `mustn't`

`⇒` Explain: In this case, when the statement is positive, we use a negative question tag. Since the auxiliary verb in this sentence is " must ", its negative form is " mustn't ".

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`3.` Somebody has taken my dictionary, _____ ___?

`⇒` `hasn't; it`

`⇒` Explain: In this case, when the statement is positive, we use a negative question tag. Since the auxiliary verb in this sentence is " has ", its negative form is " hasn't ". Because somebody is singular and we don't know what gender is what person so, we'll use it as the subject.

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`4.` Nothing can be done at this very moment, _____ ___?

`⇒` `can't; it`

`⇒` Explain: In this case, when the statement is positive, we use a negative question tag. Since the auxiliary verb in this sentence is " can ", its negative form is " can't ". Because “nothing” is always singular, even when it’s followed by a phrase stating an exception that contains a plural noun so, we'll use it as a subject.

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`5.` You have never seen that movie before, _____ you?

`⇒` `haven't`

`⇒` Explain: In this case, when the statement is positive, we use a negative question tag. Since the auxiliary verb in this sentence is " have ", its negative form is " haven't ".

$\text{@Florence123}$