MongoDB的数据类型为（） A.Key-Value B.Key-Value C.

厚壁和薄壁轴瓦的白合金和铜铅合金轴瓦的瓦壳一般采用（）

A．低碳钢

B．中碳钢

C．铸钢

D．低碳钢和铸钢

小麦茎的高度是由一对等位基因D和d控制的。下表是有关小麦茎高度的四组杂交实验结果。根据表格所给信息分析回答

(1)根据组合________的结果能推断出显性性状的是________。

(2)组合________中的两亲本肯定都是纯合体。

(3)组合________的杂交方法为测交。

(4)写出A组合中两亲本的可能基因型________。

正常人尿液最高比重与最低比重之差不应低于（）

A.0.005

B.0.002

C.0.030

D.0.009

E.0.010

活塞的对中及活塞杆的径向跳动有何影响？

An internet is a combination of networks connected by (1).When a datagram goes from a source to a(2)，it will probably pass many (3)until it reaches the router attached to the destination network. A router receives a (4)from a network and passes it to another network. A router is usually attached to several networks. When it receives a packet, to which network should it pass the packet? The decision is based on optimization: Which of the available (5)is the optimum pathway?

空白（4）处应选择（）

A.destination

B.resource

C.packet

D.source