阅读短文，根据短文内容判断正误，正确的填A，错误的填B。
American doctors say that mothers who smoke before their babies are born may slow the growth of their
babies' lungs. They say reduced lung growth could cause the babies to suffer breathing problems and lung
diseases later in life. Doctors in Boston, Massachusetts studied 1,100 children. The mothers of some of the
children smoked, the other mothers did not. Doctors found that the lungs of the children whose mothers
smoked were 8% less developed than the lungs of the children whose mothers did not smoke, and that the
children whose mothers smoked developed 20% more cold and breathing diseases than other children later
in life.
Another recent study found that children had a greater chance of developing lung cancer if their mothers
smoked. The study also showed that the danger of lung cancer increased only for sons and not for daughters,
and that the father's smoking did not affect a child's chance of developing lung cancer.
( )1. Doctors in Boston studied 1,100 children to look into the effect mother's smoking had on their children.
( )2. Mothers who smoked did not reduce the growth of their children's lungs.
( )3. The lungs of the children whose mothers smoked were 8% less developed than those of other children.
( )4. Suppose John's father was a heavy smoker, so was Mary's mother. According to the text, neither John
nor Mary has the chance to develop lung cancer.
( )5. The text is to warn us of the danger of smoking before children.
周长（一定），是和一定，不是乘积或比值一定，不成比例，此句正确；