问题

_______ the difficult maths problem, she has consulted Professor Liu several times.

A:Worked out
B:To work out
C:Having worked out
D:Work out

正确答案是：

同类题型

Which of the underlined parts is pronounced differently from the other three

Have you been to New Zealand?— No I’d like to, ________

I used to earn _______ than a pound a weekwhen I first started work

下列各句中，没有语病的一句是

The house price _______ so rapidly in many cities last year that many people couldn’t afford to buy the houses.