1£®Those who made no mistakes in today's exercises please raise your hands.

2£®What do you think of the holiday that/which we spent together last year?

3£®The children£¬all of whom had played the whole day long£¬were worn out.

4£®Many countries are now setting up national parks where animals and plants are protected.

5£®Are you willing to join the group whose goal is to protect the endangered animals in the USA?

6£®Among the many dangers which sailors have to face, probably the greatest of all is fog.

7£®The air quality in the city£¬as is shown in the report£¬has improved over the past two months.

8£®Robert spent four years in college, during which time he learned law and medicine.

9£®The days are gone when physical strength was all you needed to make a living.

10£®The thought of going back home was all that kept him happy while he was working abroad.