下列各项中,属于外来原始凭证的有( )。
A. 销售商品发票
B. 火车票
C. 缴纳电费取得的增值税专用发票
D. 汇总原始凭证
E. 购进材料取得的普通发票
A ( )is one that is controlled by hand.
( )are commonly used in motor control applications to start and stop motors.
( )provide visual indication of the status for many motor-controlled processes permitting personnel at remote locations to observe the current state of the operation.