Make sure you save all your work on screen____the computer breaks down.
A.in case B.as if C.so that D.even though
I ______ have worried before I came to the new school, for my classmates here are very friendly to me.
A.mightn’t B.mustn’t
C.needn’t D.couldn’t
Everyone on this planet is different, and that's______ makes it such a beautiful place.
A.When B.how C.what D.why
English is a language shared by several diverse cultures, _________ uses it differently.
A.all of which B.each of which C.all of them D.each of them
(2015·天津) __________ for two days, Steve managed to finish his report on schedule.
A.To work B.Worked
C.To be working D.Having worked
The ringing bell ________the end of the last class on Friday afternoon. Students rushed out of the classrooms and headed back to their dormitories.
A.confirmed B.predicted
C.indicated D.instructed