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共找到 16 与4He 相关的结果，耗时0 ms
说出下列符号的含义：S的三种含义,N的两种含义,2Na,3Mn,4Al,3C,2F,3Ne,
4He
,H+,Ba2+
化学
H______ is more important to us than money1.it was so drak that i could h____ see anything 2.the child couldn't keep his b_____ on his
英语
new bicycle,so
1He gave his to (helping the Chinese people) 2Norman Bethune was born (in 1890 )3He went to the front to (look after injured solders)i
英语
the First Wor
(D+),氢分子离子(H2+),(
4He
+)(4在上方）的电荷数,质量数.还有为什么D+叫氘核
物理
已知，如图O为圆心，∠AOB=120°，弓形高ND=2cm，矩形EFGH的两顶点E，F在弦AB上，H，G在弧AB上，且EF=4HE，求HE的长．
数学
已知，如图O为圆心，∠AOB=120°，弓形高ND=2cm，矩形EFGH的两顶点E，F在弦AB上，H，G在弧AB上，且EF=4HE，求HE的长．
数学
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