Children’s brains can’t develop properly_______ they lack protein(蛋白质).

“Take a look at these pictures, and see if you can _____ the criminal． ” The policeman said to the witness．

I thought he hated the TV .You are right,____ he still watches the program

Don`t forget the day ______you were received into the Youth League.

Was it at the school ______ was named after a hero _____ he spent his childhood?