Air pollution is caused ________(1) ill health in human beings. In a lot of countries, there are ________(2) limiting the amount of smoke factories can produce although there is not enough _______(3) on the effects of smoke on the atmosphere. Doctors have ________(4) that air pollution causes ________ (5) diseases. The gases from the exhausts of cars _______(6) also increased air pollution in most cities. The ________ (7) of petrol produces a poisonous gas, which is often collected in busy streets circled by high buildings. Children _______(8) in areas where there is a lot of lead in the atmosphere can not think as ________(9) as other children, and are clumsy when they _______(10) their hands. 
1.    A. from         B. on             C. over         D. of
2.    A. laws         B. ideas         C. problems         D. regulations
3.    A. news         B. article         C. information     D. newspaper
4.    A. agreed         B. pointed         C. disagreed         D. proved
5.    A. lung         B. heart         C. liver         D. stomach
6.    A. had             B. have         C. has             D. having
7.    A. water         B. lead         C. gas             D. exhaust
8.    A. lived         B. live             C. to live         D. living
9.    A. quick         B. slowly          C. quickly         D. slow
10.    A. touch         B. use             C. handle         D. collect