读河套平原周边地区图，完成下列各题。造成河套平原土壤次生盐碱化的原因有（）①地下水位

下图所示中的A、B、C三图依次表示酶的浓度一定时，反应速度和反应物浓度、温度、pH的关系.请根据图回答下列问题：

(1)．图A中，反应物达到某一浓度时，反应速度不再上升，其原因是：__________。

(2)．图B中，a点所对应的温度称___________。

(3)．将装有酶与反应物的甲、乙两试管分别放入12℃和75℃水浴锅中，20分钟后取出转入37℃的水浴锅中保温，两试管内反应分别为：甲______________；乙____________。

(4)．图C表示了______________催化反应的速率变化曲线。

A．唾液淀粉酶 B．胃蛋白酶 C．胰蛋白酶 D．植物淀粉酶

生态系统中最基本、最关键的生物组成成分是________。

Great news! Summer Camp 2011 opens between 9:30 a.m. and 11:30 a.m. on June 30th. And it will last for a week.

All children aged 7-14 are welcome. Each child can take part in only one of the following activities and needs to pay 150 yuan for it.

　 1. Sports (basketball, football, table tennis, etc.)

　　2. Learn in groups (painting, singing, dancing, piano, computer, etc.)

　　3. English Worlds (songs, films, games, plays, etc.)

　　Some American children are coming to the camp. If you really want to spend an interesting summer holiday, please join us for learning with fun. Act now! Book your seat as soon as possible either by phone or by e-mail. Register (报名) and pay before June 18th, then you can have a Mickey T-shirt as a member of the camp.

　　Dongfang Children's Palace: No. 23, East Street, Changping

　　Tel: 83212563  E-mail: dsbc1234@childrenplace.net

小题1:The register time is before _____.

A．9:30 to 11:30 a.m.

B．June 30^th.

C．150 yuan.

D．June 18^th.小题2:Each child can only choose _____ of the activities.

A．one

B．two

C．three

D．four小题3:What cannot you do in Summer Camp 2011?

A．Learn painting and dancing.

B．Join a group that you are interested in.

C．Climb mountains and see birds.

D．Speak English with some American children.小题4:Summer Camp 2011 will offer you _____.

A．a Mickey T-shirt

B．a piano or a computer

C．some books and CDs

D．a funny camp card

牙槽骨的生物学特征不包括（）。

A.牙槽骨是高度可塑性组织

B.是人体骨骼最活跃部分

C.随着牙的移动不断改建

D.受压力侧的牙槽骨增生

E.牙缺失后会吸收

It is commonly accepted that we should be concerned about our own physical health. The desire to take responsibility for all aspects of our physical condition, however, produces a number of negative consequences. By focusing exclusively on our physical health, we tend to ignore our mental health.
Therefore, although we can derive physical benefits from our preoccupation with physical health, we often do so at the expense of our mental health.
The author establishes her position in the passage by doing which one of the following

A．She defends her position and then extends it into a second area.

B．She reveals a contradiction in a position commonly held to be correct.

C．She supports a commonly held point of view by providing additional evidence.

D．She first states her position and then qualifies it with a number of concessions.

E．(E) She argues that a popular position can lead to problems if taken to an extreme.