问题

Sales of CDs have greatly increased since the early 1990s, when people_____to enjoy the advantages of this new technology

A:begin
B:began
C:have begun
D:had begun

正确答案是：

同类题型

The trapped children ______ what had happened.

What are you doing this afternoon—My computer is broken. I have to have it repaired this afternoon.

下列关于文学常识的表述不正确的一项是（）

He made a fire _______ himself _______ warm.

_____ all the seats full, he had no choice but to stand up.