網(wǎng)校每日一練免費(fèi)在線測(cè)試系統(tǒng)將為所有學(xué)員免費(fèi)提供練習(xí)題，所有學(xué)員登錄成功之后即可免費(fèi)練習(xí)。如有疑問(wèn)可以到答疑板與專家進(jìn)行交流，24小時(shí)之內(nèi)即可得到滿意答復(fù)。歡迎大家積極參與！

　　補(bǔ)全短文

　　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.

　　【正確答案】 B

　　【答案解析】前一句講的是科學(xué)家們過(guò)去對(duì)二手煙的看法，接下來(lái)應(yīng)選表示他們改變觀點(diǎn)的句子，因?yàn)橄乱痪浔砻魉麄兯�持的觀點(diǎn)已與過(guò)去截然不同。