kilometers in an afternoon.

像我这样的年纪，身体健康而且能在一个下午骑车跑20公里使人感到惊奇。

2. This will _______ sexual fluids ________ from one person to another.

这可以防止性交时产生的体液的传入。

3. Your mother tells me that you _____ ______ _____ and that you are finding _____difficult to give up.

你妈妈告诉我，你已经开始吸烟了，而且还很难将其戒掉。

4. You can ______ ________ ________ ______nicotine, which is one of the hundreds of chemicals in cigarettes. You can also become addicted _________ habit. Lastly, you can become__________ _________.

你会在身体上对尼古丁有瘾，它是香烟里几百种化学物质之一。你也可能因为习惯的原因而上瘾。最后，上瘾还有心理上的原因。

5. I didn't know it could _________ ________ ________ ______your heart and lungs or that it was more difficult for smoking couples to _________ __________.

我不知道抽烟能严重侵害人的心脏和肺部， 也不知道吸烟的夫妇生育能力会下降。

6. When I was ________ _________the school football team because I was too slow, I knew it was time to________ __________.

当我因为速度慢而被校足球队除名后，我才知道是我该戒烟的时候了。