题目内容：

完成句子（用名词从句）
________________（他们什么时候动身） hasn't been decided yet.
________________（Tom去哪儿了）is not known yet.
________________（他是如何成为一个科学家的）is known to all.
________________（人们为什么干这件事）wasn't quite clear.
________________（你所告诉我的）really true?