supermarkets have high levels of lead (铅), which can be dangerous to humans"可知。

　　6．The underlined word "them" in Paragraph 3 refers to "________"．

　　A．bags B．foods

　　C．supermarkets D．officials

　　解析：选A　代词指代题。根据第一段可知购物袋中的铅超标，因此，佛罗里达州的一家报社购买购物袋来检测其中的铅含量。故them在此指代bags。

　　7．Lead in shopping bags will probably come out when ________.

　　A．food is put in them

　　B．they are thrown away

　　C．they are put with other rubbish

　　D．the paint is separated from them

　　解析：选D　细节理解题。根据第三段末句的"paint (油漆) on the bags can break off and the bags can wear out. When this happens, lead can be freed"可知，环保购物袋外面的油漆脱落和袋子破损后，里面的铅就开始释放出来。

　　8．What's the best title for the text?

　　A．The return of paper bags

　　B．Time to invent greener shopping bags

　　C．The safety of shopping bags

　　D．Look out for reusable shopping bags

　　解析：选D　标题归纳题。从全文看，本文主要表达了对环保购物袋安全性的担忧，故D项作标题贴切。

　　C

　　If your dog or cat is eating grass, it means it's going to rain.

　　False (错误的) - maybe. There's no evidence (证据) that when a dog or cat is eating grass in the front yard it's going to rain. But then, there's no evidence that it isn't going to rain, either. Doctors think dogs and cats eat grass to help make their stomach better or maybe just because they like the taste of it.

　　You'll get sick if you go outside in cold weather with wet hair.

　　False. You might feel cold, but you can't catch a cold because you were outside with wet hair.

Many churches have prevented people from throwing rice at weddings (婚礼) because the rice grows larger in a bird's stomach when eaten, causing the bird to explode (爆炸)．