Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.

Câu hỏi

Some of my friends ____ volunteer work for many years, but I only _ last summer.

A. did/ started

B. are doing/ have started

C. have done/ started

D. have done/ have started

Some of my friends __________ volunteer work for many years, but I only _______ last summer.