单项选择题
An employer may know when employees are under stress because______ .
A．they will give a warning signal
B．the outward signs are always visible
C．consumption of cigarettes may increase
D．they are always unhappy
A．they will give a warning signalB．the outward signs ar……
An employer may know when employees are under stress because______ .
A．they will give a warning signal
B．the outward signs are always visible
C．consumption of cigarettes may increase
D．they are always unhappy