He had learned more than 5000 English words ______he entered the univerisity at the age of 16.
A. while
B. when
C. but
D. although
查看答案
Henry looked very much______when he was caught cheating in the math exam.
A. discouraged
B. embarrassed
C. disappointed
D. bewildered
下列属于测控电路的功能是
A. 放大与滤波
B. 调制与解调
C. 细分与辨向
D. 运算与转换
测量电路处理的信号分为
A. 模拟信号
B. 离散信号
C. 采样信号
D. 数字信号
光电开关输出信号属于
A. 数字信号
B. 模拟信号
C. 增量码信号
D. 绝对码信号
微信支付 
支付宝支付