在培养基连续灭菌操作中，灭菌作用是靠灭菌操作的（）阶段完成的。 A.预热阶段 B.升

甲、乙两个物体质量之比为3：4，已知甲物体的重力为600N，则乙物体的质量为多少千克？（g=10N/kg）

阅读理解。

      In my long years of teaching, I often ask my student to read the texts until they can recite them, and I tell

them that recitation is an important part of their homework. However, some of my students are tired of doing

so, thinking that it is both hard and useless. They argue that it takes a long time to recite a text from memory

and text itself never appears in a test paper.

      In my opinion, it naturally takes time to recite a text, but it is worth doing so. When you are able to recite

a text, you are sure to be familiar with the words and expressions. When you need them in reading or writing

or doing exercises, they will come to your mind quickly, and so you will give quick response to all kinds of

language situation. How can we say that it is useless?

      Besides, many students complain that they soon forget what they were once able to recite. This is true,

but you don't need to worry. While you are reading and forgetting the texts, your language level is being raised.

Sure you don't remember your Chinese texts that you once read in the primary school, but now you are able

to read novels and newspaper. So, recitation of the texts will help you improve your language ability.

1. The writer often asks his students to recite the texts, ______. [ ]

A. But they don't like to do so

B. And they are eager to do so

C. But they wrote a letter to the Department of Education reporting the thing

D. But they do more exercises instead of reciting the texts

2. What do the students think about the teacher's advice? [ ]

A. The English teacher tries his best to help them with English.

B. The English teacher is very kind to them.

C. The English teacher asks them to do something useless.

D. The English teacher should let them study on their own.

3. According to the text, which of the following is correct? [ ]

A. The teacher thinks the students are too naughty to learn English well.

B. The students think they spend a lot of time in reciting the texts and get nothing.

C. The students say that they often forget the words.

D.  The students take no interest in English.

4. When the students are against his suggestion, the writer ______.[ ]

A. often criticizes them

B. patiently explains to them why they should recite the texts

C. wants to give up his idea is afraid that he

D. is criticized by the headmaster.

5. Why does the writer suggest that the students recite the text? [ ]

Reciting the texts can improve the ability of applying English.

Reciting the texts is the best way of learning English.

The students should remember all the texts that the teacher has taught them.

Reciting the texts can greatly improve the classroom teaching.

当被测压缩机的出口压力波动剧烈且频繁时，应安装（）

A.隔离罐

B.缓冲器

C.分离器

D.过滤器

瓦斯保护

警告标志形状为（）。

A、圆形

B、长方形或正方形

C、顶角朝上的等边三角形