A.CH3CH2CH2CH3
B.CH3CH═CHCH3
C.CH2═CHC≡CH
D.HC≡CCH3
答案:C
I can't leave. She told me that I _____ stay here until she comes back. [ ]
A. can
B. must
C. will
D. may
丝绸之路经济带的龙头带动城市是()。
A.连云港
B.郑州
C.西安
D.没有龙头带动城市