【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.
