同學(xué)們，經(jīng)過平日的認真學(xué)習(xí)，你一定積累了好多詞匯，想不想檢驗一下你的詞匯量？你知道哪些含有字母n的單詞呢？完成下面的字謎吧！一定要保證填入的單詞不重復(fù)喲！

腦筋急轉(zhuǎn)彎

A ship can contain only fifty persons. Now there are already forty-nine persons in it. At that time， a pregnant woman comes on and boards the ship. The ship sinks. Why？