Zhou Jielun is a good __________.[ ]
A. sing
B. sings
C. singer
答案：C
Please remember to __________ the light when you leave.
A. turn off B. turn on C. turn down
"隐含的要求"是顾客和其它相关方的（）
A.合同约定
B.法规
C.共同协商
D.惯例
