Challenges with Direct Objects
Challenge 1: Compound Direct Objects
A verb may have two direct objects.
Bob hit the trash can and the mail box on his way out of the driveway.
Challenge 2: Direct Objects in Questions
In a question, the direct object may be the interrogative pronoun what, which, or whom. It cannot be where, how, or when. They are adverbs. Sometimes it helps to keep all the words in the sentence and turn it into a declarative sentence.
What did you buy? (You did buy what.)
Whom did you see at the mall? (You did see whom at the mall.)
Which is mine? (Mine is which.)
The interrogative pronoun, however, could be acting as an adjective modifying the direct object.
What color do you like best? (You do like what color best.)
Whose books do you read? (You do read whose books.)
Which figurine did you buy in Japan? (You did buy which figurine in Japan.)
The direct object may also be a noun in the sentence, but the noun may not be where you expect it to be.
Where will you spend your summer? (You will spend your summer where.)
How many books have you read? (You have read how many books.)