The National Association for Sport and Physical Education says twenty to thirty students in a P.E.class should be the limit.
VOA: special.2009.08.06
Submitted by e-mail by 5 p.m.
东部标准时间下午五点前通过电子邮件提交。
We can go all the way down -- magnesium aluminum, all the way to this noble gas, 3s23p6 argon, which would be n e and then 3 s 2, 3 p 6.
我们可以继续,镁,铝,一直到惰性气体,氩它是Ne然后。
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