[填句补文]The smoke that comes from a lit cigarette contains many different poisonous chemicals. In the past， scientists did not think that these chemicals could harm a nonsmoker‘s health. ________. They discovered that even nonsmokers had unhealthy amounts of these toxic (有毒的) chemicals in their bodies.
A、The Gilsons have been married for 35 years.
B、Recently， though， scientists changed their opinion after they studied a large group of nonsmokers.
C、We cannot avoid secondhand smoke in restaurants.
D、In the United States， nine million children under the age of five live in homes with at least one smoker.
[填句补文]David Guterson and his wife teach their three children at home. Guterson says that his children learn very differently from children in school： ________. For example， when there is heavy snowfall on a winter day， it may start a discussion or reading about climate， snow removal equipment， Alaska， polar bears (北极熊)， and winter tourism. A spring evening when the family is out watching the stars is a good time to ask questions about satellites and the space program.
A、Some parents prefer teaching their children at home because they do not believe that public schools teach the correct religious values.
B、Learning starts with the children‘s interests and questions.
C、Interestingly， results show that home-schooled children quite often do better than average on national tests in reading and math.
D、Critics also say that most parents are not well qualified to teach their children.