Why many adolescents (青少年) have trouble communicating with their parents lies in _____we call “generation gap.”

The pregnant woman worker tried to to the manager that laying her off was unfair.

_____ the ups and downs in my life, I eventually realized what life was all about.

We need ________ at the hotel for a few days because of the heavy snow.

There’s someoneknocking on the door Who _________ it be—It must be John He promised to be here at 8:00