Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions. The visitors were complaining in the rain.
A. for waiting
B. me about waiting
C.about having to wait
D.that they have to wait
* Đáp án
* Hướng dẫn giải
Đáp án là C. complain to someone about (doing ) something: phàn nàn với ai về