Question

Ask about silver. (what/use for?) ________________
Choose appropriate question using given words:
A) What silver is used for
B) What has silver been used for
C) What is silver used for
D) What silver has been used for

Answer 1

Hint: In the given sentence the subject is ‘silver’ and the verb is ‘use’. We have to fill up the blank in such a manner that the subject receives the action of the verb.

Complete answer:
Points to remember before choosing the correct option -
- When in a sentence, the subject receives the action of the verb, it is said to be written in passive voice. (We know that we have to write in a passive voice because if we look at the options the main verb is given in its participle form.)
The sentence formation in an interrogative form is as follows:
- Question word(may or may not be used) +modal/auxiliary verb + subject + base form of the main verb.
Interrogative sentences in passive voice are written in the following form:
- Question word(may or may not be used) +modal/auxiliary verb + subject + past participle form of the main verb.

Let us analyze the given options:
A) Incorrect answer - The subject precedes the auxiliary verb in this option which is grammatically incorrect.
B) Incorrect answer - We cannot use ‘ has been’ form of ‘to be’ because ‘has been’ implies a situation of present perfect. In the question, it is given ‘ ask about silver’ which implies asking in general and not based on any time period. Therefore, we will use the simple present form of ‘to be’. Thus, this option is incorrect.
C) Correct answer- This is the correct option because it uses the simple present form of ‘to be’ and past participle form of the main verb ‘ use’. Its grammatical construction is also right.
D) Incorrect answer - This option is written in an incorrect form as the subject is preceding the auxiliary verb in the sentence. Therefore, this is an incorrect option.

Therefore the correct answer is option ‘C’.

Note: The conversion of active to passive is different for different types of sentences. In fact, it is different for differently constructed interrogative sentences as well such as questions without question words, questions with question words, questions in simple present and questions in simple past will all have a different form.