Topic: Right Form of Verb,

Best Answer Explained in Below-:

In the sentence "Have you finished — that book yet?", the word that fits best in the blank is "reading." The structure of the sentence implies that the speaker is inquiring about the completion of an ongoing action, specifically the action of reading the book.

The verb "finished" is typically used with the gerund form (the -ing form) when referring to an action rather than a discrete object. Here, "finished reading" suggests that the subject has completed the process of reading, which aligns perfectly with how we naturally use this phrase in English.

Looking at the other options:

A) "to read" suggests a future action or intention and does not fit grammatically as it alters the meaning.

C) "by reading" indicates a method of completing an action but does not directly address whether the action of reading is completed.

D) "with reading" implies concurrent actions rather than the completion of reading, making it an awkward fit here.

Thus, "reading" is the correct choice, as it precisely conveys the intended question regarding the completion of the activity of reading that book.