问题 选择题

蚊虫叮咬时分泌的蚁酸(CH2O2)会使人皮肤肿痛。有关蚁酸说法正确的是 (    )

A.蚁酸是由碳、氢、氧三种原子构成

B.蚁酸中碳、氧元素的质量比为1︰2

C.蚁酸是氧化物

D.蚁酸中氢元素的质量分数最小

答案

D  

题目分析: 由化学式CH2O2可知:A.蚁酸是由分子构成的,其分子由碳、氢、氧三种原子构成,选项说法错误;B.蚁酸中碳、氧元素的原子个数比为1︰2,其质量比为:12:16×2=3:8,选项说法错误;

C.氧化物只含两种元素,而蚁酸含有碳氢氧三种元素,选项说法错误; D.蚁酸中碳、氢、氧三种元素的质量比为:12:2:16×2=6:1:16,可知氢的相对质量最小,故其质量分数最小;故选D

阅读理解

阅读理解。

     You have heard of Webster Toys. Webster's have made good, safe, interesting toys for more than a

hundred years. Now we sell them, and children play with them, in countries from New Zealand to Norway,

and from Japan to Brazil. We're looking for someone to sell our toys in the Far East. He (or She) will be

between the age of thirty and forty. He (or She) will already have some years of selling in world market

behind him (or her). He (or She) will speak good English, and at least one other language of the Far East. 

     The person we are looking for will live in Singapore, and work in our office there, but he (or She) will

trayel for up to six months in any one year. He (or She) will know the Far East quite well already. He (or

She) will understand money, and make more than ever before, for himself (or herself), and for Webster

Toys.

     Webster's want someone who can stand on his or her own feet. If you think you're the person we're

looking for, write to Mr. J. Sloman at our Head Office.

     Webster Toys Ltd.

     Church Mill, Watford.

     Herts, WD36HF.

1. Children play with Webster toys ____. [ ]

A. only in countries a long way from each other

B. in only four countries of the world

C. only in New Zealand, Norway, Japan and Brazil

D. all over the world

2. "He (or She) will already have 'some years' of selling in world market behind him (or she)" means ____. [ ]

A. he (or she) has already sold things in different parts of the world

B. he (or she) has sold toys for some years

C. he (or she) has some experience of selling in the world market for some years.

D. he (or she) has sold toys all over the world

3. The person will speak ____. [ ]

A. English and only one other language

B. English and a Far Eastern language

C. English or any other language

D. English or any other Far Eastern language

4. He (or She) will live in Singapore ____. [ ]

A. for at least 6 months in any one year

B. all through the year

C. for less than six months a year

D. for up to 6 months

5. "someone who can stand on his (or her) own feet" means some-one who ____. [ ]

A. doesn't stand on other people's feet

B. can understand money

C. understand many languages

D. can work by himself or herself

单项选择题