问题 单项选择题

根据下面的概念图可知,叙述正确的是()

A.A表示的碱基有5种

B.D表示脱氧核苷酸

C.D表示的结构有8种

D.B表示的是核糖

答案

参考答案:B

解析:

由于E是DNA,因此可知D是脱氧核苷酸,脱氧核苷酸由磷酸、脱氧核糖和碱基(ATGC)组成,故B正确。

考点:本题主要考查DNA的结构和功能,意在考查考生能理解所学知识的要点,把握知识间的内在联系,形成知识的网络结构的能力。

阅读理解

阅读理解。

     Do you know of anyone who uses the truth to deceive (欺骗)? When someone tells you something that

is true, but leaves out important information that should be included, he can give you a false picture.

     For example, some might say, "I just won a hundred dollars on the lottery ( * * ). It was great. I took

that dollar ticket back to the store and turned it in for on e hundred dollars!"

     This guy's a winner, right? Maybe, maybe not. We then discover that he bought $200 worth of tickets,

and only on e was a winner. He's really a big loser!

     He didn't say anything that was false, but he left out important information on purpose. That's called a

half-truth. Half-truths are not technically lies, but they are just as dishonest.

     Some politicians often use this trick. Let's say that during Governor Smith's last term, her state lost one

million jobs and gained three million jobs. Then she seeks another term. One of her opponents (对手) says,

"During Governor Smith's term, the state lost one million jobs!" that's true. However, and honest statement

would have been, "During Governor Smith's term, the state had a net gain of two million jobs."

     Advertisers (广告商) will sometimes use half-truths. It's against the law to make false statements so they

try to mislead you with the truth. An advertisement might say, "Nine out of ten doctors advised their patients

to take Yucky Pills to cure toothache." It fails to mention that they only asked ten doctors and nine of them

work for the Yucky Company.

     This kind of deception happens too of often. It's a sad fact of life: Lies are lies, and sometimes the truth

can lie as well.

1. How much did the lottery winner lose?

A. One hundred dollars.

B. Two hundred dollars.

C. Three hundred dollars.

D. Four hundred dollars.

2. We may infer that the author believes people should _____.

A. buy lottery tickets

B. make use of half-truths

C. not take anything at face value

D. not trust the Yucky Company

3. What do the underline words "net gain" in Paragraph 5 mean?

A. final increase

B. big advantage

C. large share

D. total saving

4. What can we know from the example of the Yucky Pill advertisement?

A. False statements are easy to see through.

B. Half-truths are often used to mislead people.

C. Doctors like to act in advertisements.

D. Advertisements are based on facts.

单项选择题