题目内容：

Are you carrying too much on your back at school? I’m sure lots of children of your age will say “Yes”. Not only do the students in China have this problem, but children in the United States also have heavy school bags.

Doctors are starting to worry that younger and younger students are having back and neck problems as a result of school bags being too heavy for them.

“It’s hard for me to go upstairs with my bag because it’s so heavy,” said Rick Hammond, an 11-year-old student in the US.

Rick is among students who have common school bags with two straps (带子) to carry them, but many other students choose rolling bags(拉杆包).

But even with rolling bags, getting upstairs and buses is still a problem for children. Many of them have hurt their backs or necks because of the heavy school bags.

But how much is too much? Doctors say students should carry no more than 10% to 15% of their own body weight.

Scott Bautch, a doctor, said children under Grade 4 should stay with 10%. But it is also important that older children don’t stay with over 15%, because their bodies are still growing. “Children are losing their balance and falling down with their school bags,” he said.

Parents and teachers are starting to tell children to only take home library books they will be reading that night. Some teachers are using pieces of paper or thin workbooks for students to take home.

One of the best answers is, as some children said, to have no homework at all!

1.From the passage we can know that        .

A. only children in China carry too heavy school bags

B. both children in China and the US carry too heavy school bags

C. children in other countries don’t carry too heavy bags

D. only children in the US carry too heavy school bags

2.If a child carries a heavy school bag,         .

A. his back or neck will be hurt    B. his head and arms will be hurt

C. his hands will be hurt    D. his feet will be hurt

3.According to Scott Bautch, if a child in Grade 5 weighs about 30 kilos, the school bag he carries should not be over ________.

A. 5 kilos    B. 3 kilos

C. 5.5 kilos    D. 4.5 kilos

4.Some students think the best answer to this problem is that        .

A. they should have a little homework to do after they get home

B. their teachers had better not ask them to do any homework

C. they should only take home library books they will read that night

D. they should use thin workbooks instead of thick ones