任务型阅读。李雷不知道该如何提高自己的英语听力水平，于是他在校园BBS上留言求助，
有四位同学跟帖回答了他的问题。
Li Lei: Hi, everyboby. I'm Jimmy. I like English very much, but I really need some advice on listening.
Who can help me?
Jenny: Don't get nervous before you start to listen to something. You need to relax. This will help.
Dr. Smith: The first sentence tells a lot the whole passage. for example, if, at the beginning , you hear
"Welcome back BBC news---", you know you will hear a piece of news, not a children's
story, or a science report.
Shirley: When you're listening, try to do some thinking. For example, you can think of the following
questions: What happened? When, Where and how? What was the result (结果) and what did
the speaker want to tell us? In this way, you may understand the passage better.
Josh: It's important for you to remember some important facts. for example, if the passage is a science
report, you should try to remember its results and how the scientists got them.
请根据以上内容完成下面任务：以下A-D是针对上述解答内容的提炼，请将它们分别与
对应的解答人配对：
A. listen to important facts.
B. listen carefully to the first sentence.
C. Relax yourself.
D. Think when you're listening.
1. Jenny: _____
2. Dr. Smith: _____
3. Shirley: _____
4. Josh: _____
请您也为李雷提供一条提高英语听力水平的建议(一句话)：
5. _______________________________________________.
的二氯代物有
中只有1种氢原子，共有1种一氯代物，一氯代物中含有4种氢原子，则二氯代物有4种，故选C。