把线段的两端无限延长，就能得到一条（ ） A．线段 B．射线 C．直线

阅读下面的短文，回答后面的问题。

     Paul got on the bus to go to the town. It was very crowded, and he had to stand for about five minutes.

Then some of the passengers got off. Paul sat down next to a fat lady. She had several shopping bags, and

Paul didn't have much room on the seat. At last the bus got to the town. All the passengers started to get off.

Paul was very polite, so he stood up to let the fat lady get off before him. She said, "Thank you." Then she

tried to get out of the seat with all her bags. But she couldn't move. She was stuck!

      Paul had to push the lady. The conductor pulled her. Finally they got her free but she wasn't pleased.

     "I'll write to the bus company," she said. "I'll tell them not to make buses with such small seats."

1. Why couldn't the lady get out of the seat?

______________________________________________.

2. When did Paul get a seat on the bus?

______________________________________________.

3. How do you know that Paul was very polite?

______________________________________________.

4. Paul didn't have much room on the seat, did he?

______________________________________________.

5. What does the underlined word "stuck" mean?

______________________________________________.

有质量相等的实心铁块和木块分别放入两个完全相同置于水平桌面上的容器中，然后分别将两个容器加满水，两物体静止后，比较两物体受到浮力F_铁与F_木、两容器底受到液体的压强p_铁底与P_木底的关系是（　　）

A．F_铁＞F_木、p_铁底＞p_木底

B．F_铁＜F_木、p_铁底=p_木底

C．F_铁＞F_木、p_铁底=p_木底

D．F_铁＜F_木、p_铁底=p_木底

下述几种纵隔肿瘤的组织来源中哪项不正确（）

A.神经源性肿瘤—起源于神经组织

B.支气管囊肿—起源于胚胎期气管芽突

C.恶性淋巴瘤—起源于淋巴组织

D.胸内甲状腺—起源于异位甲状腺或颈部甲状腺

E.胸腺瘤—起源于残留胚胎组织

“礼以行义，义以生利，利民，政之大节也”出自（）

A.《论语》

B.《孟子》

C.《大学》

D.《左传》

被誉为“社会减震器”，是保持社会稳定的重要条件，这体现的是保险的______功能。

A．社会保障管理 B．社会风险管理
C．社会关系管理
D．社会信用管理