all, 57 such trains are expected tobe in ____ commercial operation by _____ end of 2009

We usually takes turns _____ cleaning, and today it is my turn______ it.

Can you tell me how many study groups there are in a class?— Generally speaking, a class often ___ 8 study groups, each with 7 group members.

Could you tell me ___ all of you think of your teacher? —She’s a good teacher.

I _____ give you this book today, but I forgot.