米勒模拟原始地球条件的实验中,火花放电的作用是模拟原始地球上的 _________ 。
闪电
细菌内毒素的成分是()
A.H抗原
B.肽聚糖
C.脂多糖
D.O抗原
E.K抗原
_____ can you get a better job in so competitive working places.
A.Working hard
B.Although you work hard
C.Only by working hard
D.As long as you work hard