证券交易所实行（）管理。 A.自律 B.他律 C.主动 D.被动

 如图，三个小球a、b、c分别用三根绝缘细线悬挂在同一点O，细线的长度关系为Oa=Ob＜Oc,三球带电后能静止在图中位置。此时细线Oc沿竖直方向，a、b、c连线后恰构成一等边三角形，则下列说法正确的是（    ）

A．a、b、c三球质量一定相等

B．a、b、c三球所带电荷量一定相等

C．细线Oa、Ob所受拉力大小相等

D．a、b、c三球所受库仑力大小一定相等

外潜伏期是指（）

A.病人受感染后所经过的时间

B.病原体在体内存活的时间

C.病原体在吸血节肢动物体内经过一段时间的增殖或完成其生活周期的某一阶段后，才具有传染性的时间

D.病原体在吸血节肢动物体内存活的时间

E.病原体在食物或水中存活的时间

3月8日，教育部长袁贵仁表示，我国将推行校长教师交流轮岗制度，让城区的优秀校长和骨干教师到乡村学校任教，让农村的孩子也能平等地接受优质教育。多数网友认为这是实现义务教育资源均衡配置、促进教育公平发展的又一有力举措。

判断（        ）

理由：

A boy and his father were walking in the mountains. Suddenly the boy fell, hurt himself, and cried, “AAAhhhhhhhh!!!” To his surprise, he heard the voice repeating, somewhere in the mountain, “AAAhhhhhhhh!!!” Then the boy cried again, “Who are you?” He received the answer “Who are you?” He thought someone else in the mountain was making fun of him, so he got angry and shouted “Foolish!” He received the answer “Foolish!”

He looked at his father and asked, “What’s going on?” The father smiled and said, “My son, listen.” And then he shouted to the mountain, “I love you!” The voice answered, “I love you!” Again the man cried, “You’re the best!” The voice answered, “You’re the best!”

The boy was surprised, but did not understand. Then the father explained, “People call this ‘Echo’, but really this is life. It gives you back everything you say or do. Our life is just a reflection（反映）of what we have done. If you want more love in the world, have more love in your heart. If you want to be successful, work hard. This can be used in everything in life. Life will give you back everything you have given to it.”

1. At first the boy cried because __________.

A. he fell and hurt himself              B. he wanted to give himself a surprise

C. he got angry with his father          D. he hoped his father would help him

2. When the boy heard the voice repeating, he thought __________.

A. it was foolish to hear other’s voice   

B. someone else in the mountain liked his voice

C. he was laughed at by someone else in the mountain

D. there were many people in the mountain

3. The word “Echo” means __________.

A. life itself       B. repeating voice   C. love in the world      D. everything in life

4. We can infer from the story that __________.

A. the boy didn’t like his father at all        B. the boy did not understand what his father said

C. people will get everything back         D. the father had his own way to teach his son

固态微型强光防爆电筒一次充满电后，可在（）年内随时使用，若长期放置不用，每隔半年补充充电4小时左右为佳。

A.半

B.3

C.2

D.1