问题 多项选择题

安装工程中常用的聚苯乙烯(PS)材料,其使用特征有()。

A.具有较大的刚度 

B.不耐沸水 

C.耐油性好 

D.高频绝缘性好

答案

参考答案:A, B, D

解析:聚苯乙烯是苯乙烯经本体或悬浮法聚合制得的聚合物。聚苯乙烯具有较大的刚度。聚苯乙烯密度小,常温下较透明,几乎不吸水,具有优良的耐蚀性,电阻高,是很好的隔热、防振、防潮和高频绝缘材料。缺点是耐冲击性差,不耐沸水,耐油性有限,但可改性。 考点 非金属材料

完形填空

People in communities have slowly been pushed apart through the years, mostly because people simply aren’t taking the time to say a simple “hello”. After considering this phenomenon, I decided I was going to change the way I got on    小题1:  others.

My opportunity came one morning when I was in the community library. I passed by a girl  小题2:  dropped her books out of her locker.  小题3:   (think) that someone else would help her pick them up, I continued  小题4:  way. However, when I had to go back  小题5:  I forgot my book, I noticed she had just finished picking them up by herself. No one had stopped 小题6:   (help) her.

“OK,” I thought to myself, “this is where I should have changed.”

My best opportunity came a few days later when I saw a man sitting by himself waiting for the library to open, so I sat down next to him and  小题7:  (begin) a conversation.   小题8:  was difficult to get started ,and even when I had to say goodbye, almost every response from my new friend had a tone (语气) of doubt in it .And who could blame him?

People aren’t used to making  小题9:  unprepared chat with a stranger. But a change, no matter how desperately it is needed, doesn’t just happen. It takes people like us to make it possible. I advise you to take a small step out of your comfort zone and try to make someone’s day a little  小题10:  

(bright) .Together, we can really make our society come closer as a whole.

单项选择题