The world is changing with every minute， and China___________ with every minute，too．（ ）
A．is changingB．had changed
C．changed
Betty ___________ hard since last term．That's why her exam results are so good!（ ）
A．has workedB．will work
C．workedD．was working
"A white elephant"means something that is useless，___________ it may cost a lot of money．（ ）
A．unlessB．untilC．sinceD．although
Sue wasn't happy because she ___________ the concert given by her favorite singer．（ ）
A．missesB．missedC．will missD．is missing
Johnson won't answer the phone if he ___________ the number．（ ）
A．knewB．doesn't know
C．will knowD．didn't know
If you want to know more about space，please ___________ the book A Brief History of Time．（ ）
A．look throughB．look around
C．look afterD．look down upon