The incomes of skilled workers went up.________，unskilled workers saw their earnings fall.

has hit the city this month — It’s high time we _______ measures tofight air pollution

We should do what we can ________ the endangered animals.—Yes, it’s our duty_________ them.

Pork is healthy ______ and tea is a healthy ______ .

It is most ________that the experts will come to the area to investigate the possible damage caused by the heavy flood.