分枝点高度是指苗木或树木主干从贴近地面处至（）分生处的距离，测定单位为米。A、顶枝B

中 * * 党在领导全国各族人民进行新民主主义革命的过程中，铸就了井冈山精神、长征精神、延安精神、红岩精神、西柏坡精神，这都是中 * * 精神的突出表现。这表明在新民主主义革命时期[ ]

①这些革命精神体现了所有中国人的共同价值追求

②这些革命精神具有深厚的民族性、鲜明的时代性和先进性

③这些革命精神成为中 * * 精神的主体

④民族精神是民族文化的结晶

A、①②

B、①④

C、②③

D、③④

据有关统计数据表明，73.6%的迷恋网络游戏的学生，都是在朋友或同学影响下开始游戏的。这启示我们[ ]

①网络游戏的诱惑力太强，我们应远离网络    

②要注意克服盲目从众心理

③要正确把握自己的好奇心    

④要增强辨别是非能力，学会拒绝不良诱惑

A．①②③    

B．①②④  

C．②③④    

D．①③④

有关主动脉瓣关闭不全的病理生理改变，下列哪项是错误的（）

A.左心室血流充盈过度

B.在心功能代偿期，左心室排血量增加

C.在心功能失代偿期，左心室排血量增加

D.左心室逐渐扩张增厚

E.左心室肌纤维伸长

What might driving on an automated highway be like The answer depends on what kind of system is ultimately adopted. Two distinct types are on the drawing board. The first is a special-purpose lane system, in which certain lanes are reserved for automated vehicles. The second is a mixed traffic system: fully automated vehicles would share the road with partially automated or manual driven cars. A special-purpose 1ane system would require more extensive physical modifications to existing highways, but it promises the greatest gains in freeway (高速公路) capacity.

Under either scheme, the driver would specify the desired destination, furnishing this information to a computer in the car at the beginning of the trip or perhaps just before reaching the automated highway. If a mixed traffic system way was in place, automated driving could begin whenever the driver was on suitably equipped roads. If special-purpose lanes were available, the car could enter them and join existing traffic in two different ways. One method would use a special onramp (入口引道). As the driver approached the point of entry for the highway, devices installed on the roadside would electronically check the vehicle to determine its destination and to ascertain that it had the proper automation equipment in good working order. Assuming it passed such tests, the driver would then be guided through a gate and toward an automated lane. In this case, the transition from manual to automated control would take place on the entrance ramp. An alternative technique could employ conventional lanes, which would be shared by automated and regular vehicles. The driver would steer onto the highway and move in normal fashion to a "transition" lane. The vehicle would then shift under computer control onto a lane reserved for automated traffic. [The limitation of these lanes to automated traffic would, presumably, be well respected, because all trespassers (非法进入者) could be swiftly identified by authorities. ]

Either approach to joining a lane of automated traffic would harmonize the movement of newly entering vehicles with those already traveling. Automatic control here should allow for smooth merging without the usual uncertainties and potential for accidents. And once a vehicle had settled into automated travel, the driver would be free to release the wheel, open the morning paper or just relax.

When driving in an automated lane, the driver ().

A. should harmonize with newly entering cars

B. doesn’t have to rely on his computer system

C. should watch out for potential accidents

D. doesn’t have to hold on to the steering wheel

涡轮机喷水的主要目的是为了：（）

A．增加转速

B．便于钻磨

C．冲洗洁净

D．降低温度