问题 选择题

某温度下,0.1mol/L醋酸溶液的pH=3。将该温度下0.2mol/L醋酸溶液和0.2mol/L醋酸钠溶液等体积混合后,混合液的pH=4.7。下列说法正确的是[ ]

A.该温度下,0.01mol/L醋酸溶液的pH=4

B.该温度下,用0.1mol/L醋酸和0.01mol/L醋酸分别完全中和等体积0.1 mol/L的NaOH溶液,消耗两醋酸的体积比为1:10

C.该温度下,0.2 mol/L醋酸溶液和0.4 mol/L醋酸钠溶液等体积混合后,混合液的pH<4.7

D.该温度下,0.2 mol/L醋酸溶液和0.4 mol/L醋酸钠溶液等体积混合后,混合液的pH=4.7

答案

答案:B

阅读理解与欣赏
阅读理解

My topic today is the Internet. It was prompted(引出)by the first letter, which I am unable to answer fully for the reasons given!

Dear David,

I’m a middle school student. Now I am preparing for a writing competition. Could you please check the mistakes in my article about using the Internet and

Give me some advice?                           No name                                                                               David writes: I’m very sorry to say that I think it would be very unfair for me to help you win a competition--- unfair to the other competitors!

But I’ll say that your article is very interesting and I wish you good luck.

Dear David,

I’m now learning English by myself. Can you introduce some useful websites where I can make friends with foreigners? Please help me.

Moonlight

David writes: Well, dear moonlight, I think you made a good choice by using the Net in your self-studies. Two very good websites I’d suggest to you are:

www.britishcouncil.org.cn and www.britishcouncil.org.cn/learn.

By the way, for those readers interested in the teaching of English, there is an Internet discussion group called ELTCSChi-L (English Language Teaching Contacts Scheme China List).

And also, a healthy warning to all my readers: If over-used, the Internet can be a WOMBAT—A Waste of Money, Brains and Time!

小题1:David is probably a ________.

A.language expert

B.computer expert

C.college student

D.club chairman小题2: What is the reason why the first letter is unable to be fully answered?

A.David is unable to think out good advice.

B.David thinks it is expected to play fair in the competition.

C.David is going to talk on another topic-Internet.

D.David finds no mistakes in that article.小题3:“www.britishcouncil.org.cn” is a (an)________.

A.English newspaper for students and language teachers.

B.website where one can join a discussion group.

C.newspaper column for answering readers’ questions .

D.website where one can make foreign friends.