of children by 2060, when each group____ to account for about one fifth of the population

The number of students in our school _________ 4000 and a number of them _______ good at playing pingpong.

Pollution is a serious ___________ in China . PM2.5 has been increasing in recent years.

Jim’s mother just wants to know　　　that makes him so nervous.

munication, a smile isusually __________ strong sign of a friendly and _______ open attitude