9. _________ either by cooling or by depriving the fire of oxygen, and most do both.
A. Working fire extinguishers
B. Fire extinguishers that work
C. Fire extinguishers work
D. The work of fire extinguishers
答案：C
分析：空格中缺主谓。A中没有谓语；B中that多余，因为句中只有一个谓语；D也没有谓语。
参考译文：灭火器的通过冷却或者减少火中的氧气的方法工作的，大多数时候两个方法都会用到。
10. The introduction of mass-production methods enabled many people _________ and gave them an unprecedented amount of mobility.
A. to purchase their own automobiles
B. their own to purchase automobiles
C. to their own purchase automobiles
D. own their automobiles to purchase
答案：A
分析：为固定结构enable sb to do sth.
参考译文：规模生产方法的产生，使得人们能够买自己的车，并获得了空前的灵活性。 |
