问题

When flint _____ to the market, these products enjoyed great success [ ]

A: introducing
B: introduced
C: introduce
D: being introduced

正确答案是：

同类题型

下列句子没有语病的一项是

He often spends much time________playing the piano.

Measures must be taken to prevent pollution ________ happily[ ]

It’s too hot. Would you mind _______ the door —_______. Please do it now.

How did you sleep last night? — Oh, I slept like a log last night What does the underlined part mean?