A.twice a day

B.three times a day

C.four times a day

D.eight times a day

答案　D

解析　细节理解题。根据第二条调查结果中30%的年长者一天洗手四次，而这个数目是"half of the number doctors recommend (医生建议数目的一半)"，故医生建议每天洗手的次数应该是八次。

3.Which of the following is TRUE according to the text?

A.We should keep from touching our faces.

B.There are less than 300 types of bacteria in the mouth.

C.A kitchen sponge can carry more germs than a toilet.

D.We should wash our hands before touching a door handle.

答案　C

解析　细节理解题。在第三条调查结果中的Step部分，作者用了一个强调句型"...it is not your toilet but your kitchen sponge(海绵) that can carry more germs than anything else？"来说明：不是你的洗手间而是你厨房里的海绵携带更多的病菌。故选C项。

4.The text probably comes from__________.

A.aguide book

B.a popular magazine

C.a book review

D.an official document

答案　B

解析　文章出处题。通读全文可知，本文显然不是书评(a book review)，也不是政府文件(an official document)。A项有较强的干扰性，但本文主要是面向公众的日常知识普及，而不是生活指导，所以本文更可能来自大众类的杂志。故选B。

(2017·安徽六安一中高二检测)

　　It is named a kind of wooden Eiffel Tower，because of the fact that there was a large wooden platform far out in the lake on which stood an improbably high diving board. It was，I'm sure，the county's tallest wooden structure and no one had ever been known to jump from it.

So it was quite a shock when our teacher，Mr David，announced that he would dive off the high board that very afternoon.