下列合同编号代码中，代表消防系统工程的是（）
A.XGX
B.XFD
C.XFM
D.YZD
参考答案：A
— I haven't got the reference book yet, but I'll have a test on the subject next month.
— Don't worry. You ____ have it by Friday. [ ]
A. could
B. shall
C. must
D. may
除氢
