2 . 根据课文内容，在空白处填入所缺的单词。

       However, he never lost his desire to destroy cholera once and for all. In     1    , doctors in those days had two     2     theories to explain how cholera spread. One theory was that bad air caused the disease. Another was that cholera was caused by an     3     from germs in food or water. Snow     4     to the second theory. It was correct, but he still needed     5    .

3 . 根据课文内容，在空白处填入所缺的单词。
       Now halfway through her exchange year, Xie Lei feels much more at home in the UK.     1     seemed strange before now appears quite normal to her. “    2     in British culture has helped,” she said. “As well as studying hard, I’ve been     3     in social activities. British people are     4     by our culture and eager to learn more about it, so I’m keen to share my culture with them. While I’m learning about business I’m also acting as a     5     messenger building a bridge between us.”

4 . 课文语法填空

When it comes to online     1    (safe), here are some     2    (guideline) for you. Firstly, the golden rule of the Internet is to leave the site     3    (immediate) when you see or read something that makes you feel     4    (comfortable). Secondly, you have to protect your privacy. Never give out your address or phone number to someone     5       might use the information     6    (steal) your identity. Thirdly, be polite to others. There is no excuse for     7    (be) rude and you don’t want to become a target for a troll or cyberbully. Trolls often use several false names so     8       they can stay on a site and cyberbullies will also write something mean but it is usually directed     9       particular people. They may also post embarrassing photos and information about those people. However, the     10    (polite) you are, the less likely it is you will be attacked.