在SQL语言中，删除表的定义以及表中的数据和此表上的索引，应该使用的语句是 。

阅读短文，选择正确答案。

    Are you carrying too much on your back to school? I'm sure lots of your age will say "Yes". Not only the

students in China have this problem, but children in the United States also have heavy school bags.

    Doctors are starting to worry about that younger and younger students are having 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 Rich Hammond, an 11-year-old

student in the US.

    Rich is among students who have common school bags with two straps to carry them, but many other

choose rolling (转动的) bags.

    But even with rolling bags, getting up stairs and houses is still a problem for children. Many of them have

hurt backs and 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 black 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 that they will be reading at

night. Some teachers are using pieces of paper or thin workbooks for students to take home.

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

1. From the passage we can learn that ______. [ ]

A. only children in China carry too heavy school bags

B. children in other countries don't carry too heavy school bags

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

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

2. Children feel it hard for them to go upstairs because ______. [ ]

A. they are too young

B. their school bags are too heavy

C. they don't know how to go upstairs

D. their parents don't always go upstairs with them

3. If a child carries a heavy school bag, ______. [ ]

A. his back and neck will be hurt

B. his head and arms will be hurt

C. his hands will be hurt

D. his feed will be hurt

4. According to the doctor, Scott Bautch, if a child in Grade 5 weigh about 30 kilos, the school bag he carries

    should not be over ______. [ ]

A. 5 kilos

B. 3 kilos

C. 5.5kilos

D. 4.5 kilos

5. Some students thinks the best answer to this problem is that ______. [ ]

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

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

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

D. they should use thin workbooks instead of thick books

关于胃黏膜脱垂，下列描述错误的是（）

A.胃窦部黏膜厚而长，比较松弛，排列紊乱

B.以突入食管多见

C.可出现消化道出血

D.同时伴有胃炎或溃疡

E.X线表现为幽门管增宽，十二指肠球底呈伞缘状

继发性甲减是指（）

A.由于垂体病变引起甲减

B.由于下丘脑病变引起甲减

C.由于甲状腺病变引起甲减

D.由于甲状腺手术引起甲减

E.由于放射性碘治疗引起甲减

放射性32P描述正确的是（）

A.发射β射线

B.平均能量为0.69MeV

C.在组织中的平均射程为4mm

D.可用于血管瘤敷贴治疗

E.半衰期为128.3天

男性，65岁。有慢性便秘多年。近半年来发现，站立时阴囊部位出现肿块，呈梨形；平卧时可还纳。体检发现外环扩大，嘱病人咳嗽，指尖有冲击感，平卧回纳肿块后，手指压迫内环处，站立咳嗽，肿块不再出现，拟诊腹外疝，准备手术治疗

术后预防血肿的措施是

A．仰卧位
B．保持敷料清洁、干燥
C．托起阴囊、伤口砂袋压迫
D．应用抗生素
E．不可过早下床活动