问题 问答题 简答题

什么是深井泵的泵效?如何计算?

答案

参考答案:

抽油机的实际产液量与泵的理论排量的比值叫做泵效。严格地讲:这只能叫做视泵效,因为要求得深井泵的实际泵效就要考虑,液体的体积系数和油管、抽油杆的冲程损失,但这样计算繁琐,而且也没有必要;因此现场中一般就以视泵效来代替实际泵效。

其计算公式为:

η=Q液/Q理X100%

式中η——深井泵效;

Q液——油井实际日产量(吨/日)

Q理——泵的理论排量(吨/日)。

单项选择题
单项选择题

(四)

The average person learns most of the 30000 ~40000 words whose meanings he or she recognizes by hearing them or getting familiar with them in the context or simply absorbing them without conscious effort. The best way to build a good vocabulary, therefore, is to read a great deal and to participate in a lot of good talks. There are relatively few words that we learn permanently by purposefully referring to dictionaries or keeping word lists. However, even those extra few are of value, and no one will make a mistake by working on developing a larger vocabulary. Here are some suggestions of how to do it.

Read plenty of good books. When you come across a new word, or a new meaning of an old word, stop and see if you can understand it from its context. If you can’t, and if you can manage without interrupting the thought of the book too much, look it up in a dictionary or ask somebody and then repeat its meaning to yourself a couple of times, If you are really conscientious, write the word and its meaning in a personal vocabulary list—preferably using it in a sentence, or you can keep a special vocabulary notebook. Go over the list from time to time. Further, try to use a new word in writing or conversation a few times over the next several days.

Listen to good talks and be alert to new words you hear or to new meanings of words you already know. Then treat them just as you treat the new words you read.

Learn and be alert to the parts of words: prefixes, suffixes and roots. Knowing them enables you to make intelligent guesses about the meaning of words.

If you are studying a foreign language, be alert to words in that language which relate to words in English. English has inherited or borrowed much of its vocabulary of 500000~600000 words from Latin, Greek, French, Spanish and German.

The phrase "be alert to" in the third paragraph may best be replaced by "()".

A.look at

B.pay attention to

C.write down

D.learn by heart