单选题 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 have breathing problems and lung illness later in life. Doctors in Boston, Massachusetts studied 1,000 children. The mothers of some of the children smoked, the other mothers did not. Doctors found that the lungs of the children whose mother smoked were 8% less developed than the children whose mothers did not smoke, and that the children whose mothers smoked developed 20% more cold and breathing illness 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.

单选题 Mother who smokes before their child is born may ______.

单选题 Doctors in Boston studied 1,000 children to ______.

单选题 If a mother smoke, the lungs of the children ______.

单选题 What disease are the children likely to have if their mother smoke?

单选题 If parents both smoke, who has a worse effect on children?