问题 选择题

自然界的水因含有许多杂质而需要净化,下列操作中不能使水得到净化的是(  )

A.蒸馏

B.活性炭吸附

C.加入肥皂水

D.过滤

答案

A、蒸馏,使水通过蒸发、冷凝处理,处理后的水中只含水一种物质,所得水称为蒸馏水,能使水得到净化.

B、活性炭吸附沉淀是利用了活性炭的吸附性,除去的是水中的异味、不溶性固体杂质以及可溶性的杂质,能使水得到净化.

C、加入肥皂水,根据产生泡沫的多少,可以检验是硬水还是软水,但不能使水得到净化.

D、过滤可除去水中不溶性杂质,所得的水尽管还含有可溶性杂质,但能使水得到净化.

故选C.

改错题

此题要求改正所给短文中的错误。对标有题号的每一行作出判断:如无错误,该行右边横线上画一个勾(√ );如有错误(每行只有一个错误,则按下列情况改正:

此行多一词:把多余的词用斜线(/)划掉;在该行右边横线上写上该词,并也用斜线划掉。

此行缺一词:在缺词处加一个漏字符(∧),在该行右边的横线上写上该加的词。

此行错一词:在错的词下划一横线,在该行右边横线上写出改正后的词。

注意:原行没有错的不要改。

I was a honest child indeed. I didn’t dare to tell lies.        小题1:           

because of my eyes often let the secret out. I remembered    小题2:           

telling a lie to my parents, and I could hard fix my eyes on    小题3:           

my father’s face, to let alone my mother’s eyes. I glanced    小题4:           

here and there, up and down, nervously.                          小题5:           

However, after I came to Beijing, I no longer have to          小题6:           

worry my nervous eyes because everything I wanted to say   小题7:           

was sent by letter. I found myself often tell small lies. I wrote 小题8:           

“I’m well in Beijing. I enjoy the food selling at the university. 小题9:           

And at the weekends, I often buy fried chickens or pork to eat.” 小题10:           

问答题