问题 选择题

己知25%氨水的密度为0.91g/cm3,5%氨水的密度为0.98g/cm3,若将上述两溶液等体积混合,所得氨水溶液的质量分数是(  )

A.等于15%

B.大于15%

C.小于15%

D.无法估算

答案

设这两种溶液的体积是V.则

0.91V×25%+0.98V×5%
0.91V+0.98V
×100%

=14.6%<15%;

故选C.

阅读理解

阅读理解。

     The summer holiday is coming, which can be a relaxing time for sleeping, eating good meals and seeing

old friends. Try to take some time off from school and spend a few weeks of fun. Here are some ideas for

planning your summer holiday.

     First of all, joining a club is a good choice! You can join a music club, a sports club or an art club. It's

good for your future development and the teachers in the club can give you good advice.

     Doing something good for society is also great. There are many volunteer (志愿的) programmes for you

to choose from, such as looking after the old or the young, cleaning the streets, planting trees or keeping the

traffic in order. You know that teens can also make the world better.

     Have you ever lived with another family? You can join in a programme called "Meeting a New Family".

Two families exchange their children for some time so that they can learn how to get on well with others.

Summer camp is still popular today.

     An English summer camp may be a good choice. You can not only make friends but also practise your

English.

1. The writer gives some ideas for ______ your summer holiday.                                                               

2. to learn drawing, you can join an ______ club.                                                                            

3. Teens can make the world better by ______ as volunteers.                                                                  

4. In an English summer camp you can ______ your English.                                                                    

5. If you are one of the children in the programme "Meeting a New Family",

    you ______ live with you own parents for some time.

填空题