混杂因素的概念是A．影响研究结果判定的因素 B．影响统计处理的因素 C．与研究的病和

problems	causes	Advice
Feeling stressed	Too much homework; Don’t have enough tome for their hobbies.	Make a plan for study and hobbies. Find time to relax as possible as you can.
Getting short-sighted  (近视的)	Too much homework; Bad reading and writing habits.	Do homework and reading in a correct way.
Fighting with each other	Don’t know how to get on well with classmates.	Make more friends and understand each other. Share your problems with them.
Feeling tired of study	Computer games’ bad influence.	Don’t be crazy about computer games. Play them just for a short time when you are tired.
Getting fat	Having more pocket money to buy snacks; Dislike doing exercise.	Use your pocket money to do something meaningful. Spend some time doing exercise every day.

小题1:There are ______ main problems in the survey.

A．four

B．five

C．six

D．seven

小题2:What problems are caused by too much homework?

A．Feeling stressed and fighting with each other.

B．Feeling tired of study and getting fat.

C．Feeling stressed and getting short-sighted.

D．Getting short-sighted and feeling tired of study.

小题3:If Simon is feeling stressed, he should __________.

A．do much more homework

B．make a plan to spend time on study and hobbies

C．donate(捐赠) his pocket money to Project Hope

D．buy some snacks

小题4:Peter is tired of study, maybe because he __________.

A．has no close friends

B．has no pocket money

C．plays too many computer games

D．gets fatter and fatter

小题5: __________ is a good way for the teenagers to stop fighting.

A．Doing less homework

B．Playing computer games

C．learning how to make friends

D．Paying no attention to each other