问题

Is there any possible way to help them get rid of such a bad habit?— To tell the truth, it’s very hardBut weon this problem trying to improve the situation

A:worked
B:had worked
C:are working
D:had been working

正确答案是：

同类题型

Leaves are found on all kinds of trees, but they differ greatly _____ size and shape[ ]

Thank you for inviting us.Tell your wife that she gave us a perfect party.—I______. See you later.

Can you tell me _______ when I called you

mes E Rothman, Randy W Schekmanand Thomas C Südhof for their discoveries of a major transport system in ourcells

All the volunteers were very tired, but of them took a rest.—They were busy looking for the missing people.