离心泵工作的必要条件是事先要给泵()。A、形成真空 B、放真空 C、灌水

A lot of studends are having all kinds of spots on the spots field. A football game is going on just now____Class 3 and class 4. We don’t know which team will ______. Look at those people over there! Some students of class 1 are practicing  the _____jump. One of them is the best high jumper in the school. He practices hard every day. Many people think he will ____the school record（记录) in the sports meet next spring. Not far away from them，some girls are preparing for a race. They _____have a 600-meter race in ten minutes. Now in the corner of the field, you can see another group of students. Their teacher is telling them __to throw discus(铁饼).   In schools, _____students love sports now.  Sports help people to keep _____. They also help people to live happily. And____doing sports on the sports field , many people will  ______good friends, too. Do you think so?

常见的网络拓扑结构有星型、环型、 【1】 和树型等几种。

下列哪项不是洗涤剂对健康的影响（）。

A.影响肝脏功能

B.影响肾上腺

C.影响免疫功能

D.影响神经系统功能

E.皮肤毒性

在我国最常见的会发展为慢性肾功能衰竭的疾病是

A．狼疮性肾炎
B．糖尿病肾病
C．慢性肾盂肾炎
D．肾小动脉硬化症
E．慢性肾小球肾炎

广州学生医保使用范围包括哪些？