在电感元件的交流电路中，已知<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/a818ffec501541eaacdc3fd4b3458bfa.png" />，则（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/70961d125a8a493cbdbd3169e8655336.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/65f4ae24f45041548b04d5bb8c113767.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/20d9ff741d534721b621dfe04fb3b2bd.png" />

电路如图4所示，电流I为。<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/48dcfd6292e44a329c2d5b04973679d8.png" /> A: 0A B: –2.5A C: 3A D: –3A

电路如图5所示，若输入信号ui为方波，则输出波形为           。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/ad0dc8cc2e8547ccb31a035a818c1d8d.png

要使<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/c4b80714c3b14a559ae5bdcd09ef1fc6.png"/>是线性方程组AX=0的基础解系，则只要系数矩阵A=（ ）. A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/fb16cbefa5a746599e585bcf30dce878.png"/> B: ［2 1 1］ C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/df5d7a834bd44f44a519eaffffd47d39.png"/> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5adacc7663b444d69f148ab2e7a11cf1.png"/>

一定量的理想气体，在温度不变的条件下，当压强降低时，分子的平均碰撞频率<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5499a59dc3754bfdbf231e19c5e2edb9.png" />和平均自由程<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/bba421d6506c4072b583fd4e63b5df81.png" />的变化情况是（ ）： A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5499a59dc3754bfdbf231e19c5e2edb9.png" />和<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/bba421d6506c4072b583fd4e63b5df81.png" />都减小． B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5499a59dc3754bfdbf231e19c5e2edb9.png" />减小而<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/bba421d6506c4072b583fd4e63b5df81.png" />增大． C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5499a59dc3754bfdbf231e19c5e2edb9.png" />和<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/bba421d6506c4072b583fd4e63b5df81.png" />都增大． D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/5499a59dc3754bfdbf231e19c5e2edb9.png" />增大而<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201804/bba421d6506c4072b583fd4e63b5df81.png" />减小．