与社会生产密切相关的运输活动,从生产过程来看,可以分成两类:一是作为具体生产过程的有机组成部分的生产内部运输,一是作为物质生产部门的运输业所从事的()
参考答案:运输活动
在下列各句的空格内填上一个适当的单词,该词的首字母已给出。
1. I can't hear you. Can you read it a_______?
2. If you work hard, you will s________ in the end.
3. His mother often teaches him the i________ of working hard.
4. Peter f______ his math test last time. He was sad.
5. Though he is much too s_______, he tries his best to keep awake.
如图甲所示理想变压器的原线圈的匝数n1与副线圈的匝数n2之比为10∶1。原线圈接如图乙所示的正弦交流电,两个阻值均为11Ω的定值电阻串联接在副线圈两端(电压表均为理想电表),则( )
A.通过两电阻的交流电频率为5Hz
B.当t=1×10-2s时,电压表V1示数为零
C.当t=1.5×10-2s时,电压表V2示数为11V
D.原线圈的输人功率为44W