问题 解答题

甲种矿石含铁54%,乙种矿石含铁36%,将两种矿石若干吨进行混合得到含铁48%的矿石,如果混合时甲种矿石比原来少取12吨,乙种矿石比原来多取10吨,那么混合后的矿石含铁45%,问原来混合时,两种矿石各取多少吨?

答案

解:设来混合时,甲种矿石x吨,乙种矿石y吨,

解得

故原来混合时甲有44吨,乙有22吨.

阅读理解

任务型阅读。

     What are the limits (极限) of human body? The BBC's Focus magazine has some answers.

How cold can you stand?

     Normal body temperature is around 37℃. At 35℃ you're unable to write your name. Even walking is very

difficult. At 33℃ you may find it difficult to think, understand and form (形成) opinions properly. By the time

you have cooled to 20℃, your heart would have stopped beating. Limit: 0℃. Ice would form in your tissues

(纤维组织), killing all the cells.

How spicy can you eat? 

     There is capsaicin (辣椒素) in many foods. The more capsaicin, the hotter the dishes are. If you're healthy

enough, you can survive (存活) eating a teaspoon of pure capsaicin. But you would find it impossible to eat

anything else for a few hours. Limit: 5g capsaicin.

How fast can you run?

     The fastest man in the world is Asafa Powell. The runner finished the 100m in 9. 74 seconds in 2007. This

gives an average (平均的) speed of 36. 96km/h. Top runners are at their fastest around 80 metres, so a runner's

greatest speed may reach 43.06km/h. Limit: 43.06km/h.

How loud is too loud?

     The loudest sound you can hear is 168 dB (分贝). Sound louder than that may do harm to your ears. The

loudest sound ever recorded was the eruption of Krakatoa (卡拉卡托火山爆发) in 1883. It was 180 dB, 160km

away.

Limit: 168 dB

根据短文内容,回答问题。

1. At what temperature will your cells die?

   ________________________________

2. What will happen if you eat a teaspoon of pure capsaicin?

   ________________________________

3. How fast can a runner run at most?

   ________________________________

4. What sound can be heard by your ears?

   ________________________________

5. Where can you read such an article?

   ________________________________

单项选择题