78. The question isn’t easy. I can't answer it. (合并为一个复合句)
The question is______ difficult ______ I can’t answer it.
77. Both of us have been to the Great Wall, (改为否定句)
______of us______been to the Great Wall.
按括号内要求改写句子。
76. You should finish your homework in an hour. (改为祈使句)
______your homework in an hour, _______.
40. China has______the WTO for some years.
A. taken part in B. joined
C. been a member of D. entered
39. Lucy’s mother told her to come back earlier, ______.
A. so she does B. so it is
C. so did she D. and so she did