30名工人做1800个零件,x小时完成,平均每人每小时加工的零件个数是_____

题型:填空题

问题:

30名工人做1800个零件,x小时完成,平均每人每小时加工的零件个数是______.

考点:写代数式
题型:填空题

如图所示,水平传送带以恒定的速率v=2.0m/s传送质量为m=0.5kg的工件,工件都是在位置A处无初速地放到传送带上的,工件与传送带间的动摩擦因数μ=0.4,每当前一个工件在传送带上停止相对运动时,后一个工件立即放到传送带上.g取10m/s2,传送带上相对静止的相邻两工件间的距离为______m.

题型:填空题

如图所示,以9.8 m/s的水平初速度v0抛出的物体,飞行一段时间后,垂直地撞在倾角θ为30°的斜面上。可知物体完成这段飞行的时间是

[ ]

A.

B.

C.

D.2 s

题型:填空题

Part 4


Questions 26-45


·Read the following passage and decide which answer best fits each space.
·Forquestions26-45, markoneletterA, B, C or D on the Answer Sheet.
Both (26) and zoology are parts of a more general field of science, biology. The two are studies of (27) things, which share certain characteristics, (28) they are plants or animals. Botany deals with plants, whose organisms that can (29) their own food by the use of sunlight. Zoology on (30) hand, deals with animals, those organisms that cannot manufacture their own food and are thus dependent (31) plants for their food.
(32) plants and animals share many abilities, the extent (33) which plants can exercise some of those abilities is (34) . For example, both plants and animals need food, water, and warmth for growth, (35) plants can move to (36) those needs only by the slow extraction of their leaves and roots, while animals can move relatively (37) distances in relatively little time. When an animal is hurt with needle, the animal will (38) the part of the body (39) . This ability to draw back (40) pain or irritation, called irritability, is found only to a very limited extent in plants.
If plants (41) the same (42) as animals, animals would have had a more difficult time finding food. If animals were as limited as plants, they might (43) a means of manufacturing their own food, as plants do now. The world would be a very different place (44) it is if the characteristics of plants and animals were (45)

A.acquire

B.require

C.admit

D.constitute

题型:填空题

与肝癌有关的不良生活习惯是()。

A.硝酸盐

B.食用黄曲霉素污染食物

C.吸烟

D.饮酒及食用发酵霉变食物

E.不洁饮食

题型:填空题

在“ * * ”中的1975年,国民经济迅速回升,其原因主要是

A.林彪反革命集团被粉碎

B.在全国范围内展开批林批孔运动

C.周恩来主持中央工作,着手调整国民经济

D.邓 * * 主持中央工作,进行全面整顿

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