用于电动葫芦及悬挂梁式起重机的滑触线有( )三种。
A．型钢
B．扁钢
C．角钢
D．圆钢
参考答案：A,B,C
He was ill , ______he still went to school on time.[ ]
A. but
B. and
C. or
D. /
