问题
选择题
冬天，可以看到户外的人嘴里呼出“白气”，这“白气”是
A．水蒸气
B．热空气
C．小水滴
D．二氧化碳
答案
答案：C
题目分析：这是一种液化现象，液化就是气态变成液态的现象。人嘴呼出的水蒸气温度较高遇冷液化成许多小水滴，所以C正确。
搜题请搜索小程序“爱下问搜题”
冬天，可以看到户外的人嘴里呼出“白气”，这“白气”是
A．水蒸气
B．热空气
C．小水滴
D．二氧化碳
答案：C
题目分析：这是一种液化现象，液化就是气态变成液态的现象。人嘴呼出的水蒸气温度较高遇冷液化成许多小水滴，所以C正确。
| Read the article, and fill in the blankets with the words given. | |
But beyond just looking dirty, a filthy (肮脏) keyboard might actually make you sick. A 2008 study showed that keyboards can be up to five times dirtier than the average toilet seat. How come? Too often, people don't 2_____ to wash their hands after using the restroom or eating at their desks. In the latter case, sticky fingers transfer sauces and crumbs (食物碎屑)onto and between the keys. Also, our fingers rub skin oils onto the keys. Thus, a keyboard can become a 3_____ place for germs to grow. One common bug that researchers have found is staphylococcus aureus (金黄色葡萄球菌). It is a classic cause of food 4_____, signs of which include nausea (恶心) and diarrhea (腹泻). Stomach sicknesses caused by typing on a dirty keyboard have been dubbed "qwerty tummy" after the "Q-W-E-R-T-Y" keys on a keyboard. The threat posed by a dirty keyboard is quite real, but it can be 5_____. The easiest way is to clean your keyboard regularly. Office cleaning 6_____ say that keyboards should be unplugged, turned upside down and shaken 7_____. By doing so, you can get rid of most of the crumbs. After that, wipe across the keys using a soft cloth with a cleaning solution (清洁剂). Another way to solve the problem is using a silicon (硅胶) keyboard cover. These thin covers are made to 8_____ over the keys. They prevent food from falling through the cracks and dust from 9_____. |