6502型电气集中控制台进站信号复示器在信号开放时亮（）。
A.红灯
B.绿灯
C.白灯
D.红灯和白灯
参考答案：B
He was sad for ________ any chance of his going to college.
A．there being not
B．there not being
C．not there being
D．not being
对现有供应商的考核指标包括（）。
A.质量指标
B.供应指标
C.经济指标
D.支持与合作指标
