He turned the radio on at 7.30. He was still liste...

Câu hỏi: He turned the radio on at 7.30. He was still listening to it when his mother came home at 9.00

A. He has been listening to the radio at 7.30.

B. He had been listening to the radio since 7.30.

C. He has been listening to the radio after 7.30.

D. He had been listening to the radio by 7.30.