几种短周期元素的原子半径及某些化合价见下表,下列说法正确的是 ( )元素代号ABDEGHIJ 化合价–1–2+4、–4+7、–1+5、–3+3+2+1 原子半径/nm0.0710.0740.0770.0990.1100.1430.1600.186 A.A的单质能将E单质从HE3的溶液中置换出来 B.A、H、J的离子半径由大到小顺序是A>J>H C.G元素的单质不存在同素异形体 D.I在DB2中燃烧生成两种化合物
________ the machine begins to work, you can't stop it ________.
[ ]
A.While; soon
B.For; right away
C.Once; at once
D.Until; immediately