单项选择题
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
You（）to lock the door at night.A.should B.oughtC.must...
单项选择题You（）to lock the door at night.
A.should B.ought C.must D.shall
