计算行列式 的值．
解：=1•2•3•4…（n﹣1）•n=n!．
The summer holidays are coming, so the twins as well as Jack ________ to Hong Kong for vacation.
今年漫长的雨期给人们的出行生活带来诸多不便，许多农村饮用的地下水浑浊，下列方法能得到纯水的是（ ）
的值．
=1•2•3•4…（n﹣1）•n=n!．