题干
George _________ too far. His coffee is still warm.
A：must have gone
B：might have gone
C：can't have gone
D：needn't have gone
答案(点此获取答案解析）
C
George _________ too far. His coffee is still warm.
A：must have gone
B：might have gone
C：can't have gone
D：needn't have gone
2SO3, 在混合气体中充入一定量的18O2, 足够长的时间后, 18O原子（ ）
