立式车床由于工件及工作台的重力由机床导轨或（）轴承承担，大大减轻了立柱及主轴轴承的负

供热管道除污器安装应符合设计要求，但无方向性要求。( )

  When you are in England, you must be very careful in the street because the traffic moves on the left. Before you cross a street, you must look to the right first then the left.

If the traffic lights are red, the traffic must stop. Then the people on foot can cross the road carefully! If the traffic lights are green, the traffic can go. People mustn’t cross. In the morning and in the evening when people go to or come back from work, the streets are very busy. Traffic is the most dangerous then.

When you go by bus in Hong Kong, you have to be careful, too. Always remember the traffic moves on the left. So you must be careful. Have a look first, or you will go the wrong way.

In Hong Kong, there are big buses with two floors. You can sit on the second floor. From there you can see the city very well. It’s very interesting.

小题1:When you cross a street in England, you must _______________.

A．look to the left then the right

B．look to the right first and then the left

C．look to the cars and buses

D．look to the left and the right at the same time小题2:If the traffic lights are red, ____________________.

A．the traffic must go

B．the people must go

C．the traffic must stop

D．the people must stop小题3:Traffic is the most dangerous___________________.

A．in the morning

B．in the evening

C．when you go to the wrong way

D．when people go to or come back from work小题4: In Hong Kong, the traffic moves _________________.

A．the same way as in most cities in China

B．on the right

C．the same way as in most cities in the UK

D．in the middle of the roads小题5: If you take a bus with two floors in Hong Kong, you can sit on the second floor because__________________________________.

A．you can enjoy a better view

B．it is cooler up there.

C．you can have a larger seat

D．it is easy for you to know the city well.

如图所示，光滑水平面上有一质量M=4.0kg的平板车，车的上表面是一段长L=1.0m的粗糙水平轨道，水平轨道左侧连一半径R=0.25m的

1

4

光滑圆弧轨道，圆弧轨道与水平轨道在O′点相切．车右端固定一个尺寸可以忽略、处于锁定状态的压缩弹簧，一质量m=1.0kg的小物块紧靠弹簧放置，小物块与水平轨道间的动摩擦因数μ=0.5．整个装置处于静止状态．现将弹簧解除锁定，小物块被弹出，恰能到达圆弧轨道的最高点A．取g=10m/s²．求：

（1）解除锁定前弹簧的弹性势能；

（2）小物块第二次经过O′点时的速度大小；

（3）小物块与车最终相对静止时距O′点的距离．

醉酒的人在醉酒状态中，对本人有危险或者对他人的安全有威胁的，应当将其拘留到酒醒。( )

下列图标表示（）

A.天线

B.电缆

C.导线