单项选择题
A.so B.however C.as D.because
Great changes （） in China since 1978.A.take the placeB....
单项选择题Great changes （） in China since 1978.
A.take the place B.took the place of C.have taken place D.have been taken place
Electricity （） by the Greeks a good many years ago.A.wa...
单项选择题Electricity （） by the Greeks a good many years ago.
A.was first found B.was first discovered C.has first been discovered D.was seen first
Before she left on the trip, she（） hard.A.trainedB.has ...
单项选择题Before she left on the trip, she（） hard.
A.trained B.has trained C.would trained D.had trained
