题目内容

下列有机物的命名正确的是()

A. 2-乙基丁烷
B. 2,2-二甲基丁烷
C. 3,3-二甲基丁烷
D. 2,3,3-三甲基丁烷

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Scientists say that laughter is ________.

A. good for us
B. serious
C. not really good
D. the worst medicine

Laughter is good for _________.

A. our whole body
B. only the face
C. only the chest and shoulders
D. only the circulation

Laughter clubs ________.

A. are only in India
B. are places to learn jokes
C. help people feel better
D. are free

Complete these sentences with the words or phrases in the box.Blood pressurecirculationmusclespainkillerbrainheartbeatorganrelaxation1. When we laugh, we use 15 different in our face.2. Laughter is good for every in our body.3. When we laugh, our goes down.4. Laughter makes our better.5. A beta-endorphin is a natural .6. Laughter makes our _ lower.7. Laughter makes a natural painkiller in our .8. Forty-five minutes of is the same as one minute of laughter.