搜题请搜索小程序“爱下问搜题”
问题 不定项选择

一长直木板的上表面放有一小木块，当木板以远离木块的一端O为轴，如图所示由水平位置缓慢向上转动（α角变大）时，则木块受到的摩擦力Ff随转过的角度α变化的图象，可能正确的是

[ ]

A．

B．

C．

D．

答案

答案：C

操作题

请在图中画出用瓶起子启瓶盖的动力F1的力臂L1和阻力F2。

查看答案
单项选择题

A local-area network (LAN) is a communications network that (125) a variety of devices and provides a (126) for information exchange among those devices. The scope of the LAN is small typically a single building or a cluster (丛) of buildings. The LAN is usually owned by the same organization that owns the (127) devices. The internal data rate of LAN is at least several Mb/s.
The basic of LAN communication is broadcasting. At each station, there is a transmitter/receiver that communicates over a (128) shared, By other stations. A transmission from any one station is (129) to and received by all other stations.

A．broadcast

B．cable

C．control

D．interconnects

E．internet

F．meander

G．means

H．medium

I．modem

J．output switch relay
查看答案