推进出站调车时，连接风管的数量为（）。A、全部 B、1/2 C、1/3 D、1/4

阅读理解。

    Wang Lei 1._____

    The most difficult thing about learning English is to remember new words. I study the words and remember

them, but a week later I have forgotten most of them. When reading something in English, I always get into

trouble when I come across a new word. There must be a better way to learn new words.

    Li Qiang 2. _____

    I have been studying English for so long now, but I don't enjoy it any more. I used to like it, but now I feel

that I'm not making any progress, I'm just not motivated (有动力的) any more. I wish there was something I

could do to make me interested in studying English again.

    Fang Zhe 3. _____

    I wish I could improve my spoken English. Every time when I take part in a group discussion or try to

speak English to someone, I find it difficult to express myself. I don't know what to say and I can't think of

the words I need.

    Huang Wei 4. _____

    I don't like English at all. Why do we have to study English? I'd rather spend more time on math and

science, because I think those subjects are more important.

    Zhong Mei 5. _____

    I think it is easy to remember new grammar rules. But when writing something, I always make a lot of

mistakes. How can I learn to use the rules that I have learned?

根据以上五位学生在英语学习中遇到的困难， 从所给的选项A-E中，选出每个人所需要读的文章。

A. How to speak good English

B. How to put English grammar to use

C. How to master (掌握) English words

D. How to realize the importance of English

E. How to get interested in English

选煤厂各职能部门负责人对本职范围内的安全工作（）。

我们生活在物质世界中，每天都要接触很多物质：如①液态氧 ②白酒 ③铜 ④自来水 ⑤空气 ⑥高锰酸钾 ⑦过氧化氢 ⑧铁粉 ⑨糖水 ⑩氮气，

属于化合物的有(填序号，下同)____，含有氧分子的有____，属于单质的有____.

兰兰有一个石头雕成的小乌龟，重约6 N，她想利用所学知识探究两个课题：

A.实际测量一下小乌龟的重力；

B.测量小乌龟完全浸没在水中时受到的浮力。

兰兰手边只有一个量程为0～5N的弹簧测力计，为了完成探究，她又找到了以下器材：轻质滑轮（滑轮重和摩擦忽略不计）、铁架台、轻质刻度尺、细线（自重不计 ）、足够大的量杯和足量的水，如图所示。请你从A、B两个课题中任选一个，并从上述器材中选择必要的器材，参照示例设计实验方案。

离心泵的性能曲线表明，扬程一般（）。

A.与流量无关

B.与流量成直线关系

C.可写为H=A+BQ2，且B>0

D.dH/dQ<0