问题
单项选择题
以下各项关于控制元件说法不正确的是（）。
A、将液体压力能转换成机械能的元件
B、通过对液体的压力、流量、方向的控制，以改变执行元件的运动速度、方向、作用力等的元件即为控制元件
C、常用于实现系统和元件的过载保护、程序控制等
D、液压系统中的各种阀类元件就是控制元件
答案
参考答案：A
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以下各项关于控制元件说法不正确的是（）。
A、将液体压力能转换成机械能的元件
B、通过对液体的压力、流量、方向的控制，以改变执行元件的运动速度、方向、作用力等的元件即为控制元件
C、常用于实现系统和元件的过载保护、程序控制等
D、液压系统中的各种阀类元件就是控制元件
参考答案：A
Directions: There are 10 blanks in the following passage. For each numbered blank, there are 4 choice marked A, B, C and D.
| During recent years we have heard much about "race": how this race does certain things and that race believes certain things and so on. Yet, the (51) phenomenon of race consists of few surface indications. We judge race usually from the coloring of the skin: a white race, a brown race, a yellow race and a black race. But (52) you were to remove the skin you could not tell anything about the race to which the individual belonged. There is nothing in physical structure, the brain or the internal organs to (53) a difference. There are four types of blood. All types are found in every race, and no type is distinct to any race. Human brains are the (54) No scientists could examine a brain and tell you the race to which the individual belonged. Brains will (55) in size, but this occurs within every race. (56) does size have anything to do with intelligence. The largest brain ever examined belonged to a person of weak (57) . On the other hand, some of our most distinguished people have had (58) brains. Mental tests which are reasonably (59) show no differences in intelligence between races. High and low test results both can be recorded by different members of any race. (60) equal educational advantages, there will be no difference in average standings, either on account of race or geographical location. |
A．true
B．exact
C．certain
D．accurate