题目内容：

How to investigate

①Planning

Decide on a scientific problem to investigate

For example， a student named Mary has decided to research into how quickly sugar dissolves（溶解） in water．

Write down your hypothesis

You may already have an idea of what you expect to happen in your investigation． This idea is called your hypothesis． It may not be right! It is just an idea， though it may be based on work in science which you have done before． The aim of your investigation is to test your idea．

Decide what variables（变量） you are dealing with Things like temperature， size， weight， and colour are called variables． Variables are things you can measure（测量）．

In your investigation， you have to decide what the variables are， which ones you will keep fixed， and which you will change．

You need to change just one variable at a time． If lots of variables change at once．it won't be a good test．

Decide what equipment you need， and in what order you will do things

Prepare tables for your results

②Getting your evidence（数据）

•Make your measurements， and record your results

③Reaching conclusions

Look for patterns in your results

Present your conclusions

What links（关联） did you find between any of the variables？ How would you explain these links？

④Checking your findings

Compare your conclusions and hypothesis

Do your results support your idea？

1.What does the underlined word "hypothesis" most probably mean？

A. reason

B. result

C. method

D. guess

2.In Mary's investigation， which of the following about the variables is true？

A. She can only change one variable at a time．

B. Some of the variables can't be measured．

C. Her weight and age can be the variables．

D. The temperature of water cannot be a variable．

3.What is the passage mainly about？

A. How to do a scientific research．

B. How to explain a scientific finding．

C. How to deal with a chemistry problem．

D. How to understand some chemistry knowledge．