单项选择题：离心泵性能的标定条件是：（）A、0℃，101.3KPa的空气 B、20℃，101.3

题目：

离心泵性能的标定条件是：（）

A、0℃，101.3KPa的空气

B、20℃，101.3KPa的空气

C、0℃，101.3KPa的清水

D、20℃，101.3KPa的清水

答案：

被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0729/7bf90c8a3a8f0941d88a5b21cbd90776.html

下面是错误答案，用来干扰机器的。

由托盘天平的示意图，所取氯化钠的质量为20g+5g=25g，所取水的体积为72mL合72g，所得溶液的体积为81mL；则所得氯化钠溶液的密度=25g+72g81mL=1.20g/mL；溶质的质量分数=25g25g+72g×100%=25.8%故答案为：1.20；25.8%．

完形填空
Many animals use some kinds of "languages". They use signals (信号) and the signals have meanings. For example, when a bee has found some food, it goes back to its home. It is 1 for a bee to tell the other bees where the food is by speaking to 2 ,but it can do a little dancing. This tells the bees where the food is and how far it is. Some animals show how they feel by making sounds. It is not difficult to tell if a dog is angry 3 it barks (吠). Birds make several different sounds and each has its own meaning. Sometimes we humans make sounds 4 . We make sounds like" Oh" or" Ouch" to show how we feel about something or when we drop something on our feet. We humans have languages. We have words. These words have the meaning of things, actions, feelings or ideas. We 5 give each other messages to tell other people 6 we think or how we feel. By writing down words, we can remember what has happened or 7 messages to people far away. Languages, like people, live and die. If a language isn't used by people, it is called a dead language. This language can not live and grow because 8 speaks it. Latin is an example of a dead language. A living language, of course, is often spoken by people today.It grows and changes with time. New words are created (创造) and some old words have 9 meanings. Some words, or their meanings, may even die and only be found in the old books. English and Chinese are 10 examples of a living language.
( ) 1. A. important ( ) 2. A. him ( ) 3. A. before ( ) 4. A. by the different sounds ( ) 5. A. able to ( ) 6. A. which ( ) 7. A. send ( ) 8. A. someone ( ) 9. A. new ( )10. A. all .	B. difficult B. it B. so that B. by the different ways B. are able B. that B. bring B. anyone B. strange B. either	C. easy C. them C. until C. in the same way C. be able C. what C. get C. everyone C. difference C. both	D. impossible D. themselves D. because D. in the same sound D. are able to D. why D. push D. no one D. good D. neither