Choose the option that completes the sentence-
Have you finished ______ the computer?
a)Using
b)To use
c)The use
d)Up the use of

Hint: Read the given sentence and understand what it means. Now, go through the options, and choose the one which agrees with the tense of the sentence and fits the context. Make sure to form a grammatically sound sentence.

Complete answer:In the given question, a gerund has to be used. A gerund is a verb form which functions as a noun, in Latin ending in -ndum (declinable), in English ending in -ing (e.g. asking in do you mind my asking you?) Gerunds are the elusive shapeshifters of the English language. They are created out of verbs, but function as nouns.
Option ‘a’ is using. It is a gerund as it can be used as a noun as well as a verb in any given sentence. So it is the correct option.
Option ‘b’ is to use. It is in the present tense and is not the correct answer.
Option ‘c' is the use. It is also an incorrect option because we cannot use ‘the’ here.
Option ‘d’ is up the use of. It is a phrase and it does not satisfy the conditions required for the blank. It is the wrong option.
Hence, option ‘a’ is the correct option.

Note:In English, a gerund has the properties of both verb and noun, such as being modifiable by an adverb and being able to take a direct object.