It is _________ pleasant to take a crowded bus

Nowadays, more and more people are using private cars, ________ has caused a lot of traffic problems, especially in large cites like Beijing and Shanghai.

The parents were shocked by______news that their sonneeded______operation on his knee.

Is it in that red building________we can learn and enjoy a rich and colorful life________about 100 Chinese paintings will be on display?

The incomes of skilled workers went up________，unskilled workers saw their earnings fall