C.

`13.` I was made to change my minds by my parents but I didn't 

`-` Make sb do sth (CĐ) `->` be made to do sth (BĐ)

`14.` I was made to tell the truth.

`-` Make sb do sth (CĐ) `->` be made to do sth (BĐ)

`15.` Why wasn't the accident reported sooner?

`-` Câu BD thì QKD: `(?)` Was/Were + S + PII + O?

`16.` We were allowed to use Mary's car yesterday.

`-` Let sb do sth: cho phép ai làm gì

`->` S + tobe + allowed + to V: ai được phép làm gì

`17.` Someone could be heard crying in the next room.

`-` S + ĐT khuyết thiếu + be + PII + O

`18.` People were watched to walking past.

`-` Câu BD thì QKD: S + was/were + PII + O

`19.` The car was seen to drive up outside the police station by Jack.

`-` S + tobe + seen + to V: ai được nhìn thấy làm gì...