In one day, Sue can change the oil on 20 cars or change the tires on 20 cars. In one day, Fred can change the oil on 20 cars or change the tires on 10 cars. Sue and Fred can gain from trade if Sue changes the ( ) and Fred changes the ( ). A: tires; oil B: oil; oil C: oil; tires D: tires; tires

Tires are important to your safety and comfort.

Clothes, tires, and cleansers injure the environment.

Properly inflated tires are more danger and wrong. ( )

One of the tires of the truck exploded because of (). (over, load)

Tires are important to your safety and comfort. A: 正确 B: 错误

（ ）Most bicyclists were willing to pay for having their bike tires filled.

Most bicyclists were unwilling to pay for having their bike tires filled.

The journey __________ me out. A: tires B: tiring C: tired D: tried

He has little trouble（）the tires of his car A: to fix B: fix C: fixing D: with fixing