One of the tennis rackets broken when they found them.[ ]
A. is
B. are
C. were
D. was
答案:D
下列物质①无水乙醇、②乙酸、③石炭酸、④苯,其中能够与钠反应放出氢气的物质是( )
A.①②
B.①②③
C.③④
D.②③④
全陪应提前( )到达接站地点与地陪一起迎候旅游团。
A.1小时
B.2小时
C.半小时
D.20分钟