下列哪条动脉损伤是导致股骨头缺血坏死的主要原因A．股骨圆韧带小动脉 B．股骨干滋养动

类风湿关节炎基本病理特点是( )

A．外分泌腺体炎
B．附着点炎
C．滑膜炎
D．关节软骨退行性变
E．皮下结缔组织增生

如图所示，一平板车以某一速度 v_o=5m/s 匀速行驶，某时刻一货箱（可视为质点）无初速度地放置于平板车上，货箱离车后端的距离为 l=3

1

6

m，货箱放到车上的同时，平板车开始刹车，刹车过程可视为做 a₁=3m/s² 的匀减速直线运动．已知货箱与平板车之间的摩擦因数为 μ=0.2，g=10m/s²．求：

（1）通过计算，判断货箱能否从车后端掉下来

（2）如果货箱不能掉下，则最终停止时离车后端的距离 d 是多少

（3）如果货箱不能掉下，最后都停止运动，平板车再从静止开始以 a₂=4m/s² 的加速度匀加速直线运动，经过 3 秒货箱距离车后端多远？已知平板车后端离地面高 1.25m，货箱落地后不动．

根据首字母提示及句意写出单词。

1. The film Big Dad is an i _____ film, I love watching it .

2. Teachers'Day is in S _____ .

3. We often go home by t _____ . I think it is safe and cheap.

4. The tiger has a lot of sharp t _____ . They are dangerous.

5. The moon shines brightly t _____ the window.

News reports say peace talks between the two countries ______ with no agreement reached. [ ]

A. have broken up

B. have broken down

C. have broken out

D. have broken in

纯净胃液pH值为

A．0.9～1.5
B．1.5～2.5
C．2.5～3.5
D．3.5～5.0
E．5.0～6.0