定语从句与动词不定式的转换,怎么转呢?

1.---Just operate the machine according to the directions by yourself.
---How can I tell which button to press
=How can I tell which button I should press.
2.The actors and actress were allowed only 15 minutes in which to change their costumes.= ...in which they should change their costomes.
3.The chairman made a conclusionwith which to end the meeting.
=...with which they should end the meeting

这个问题。。。。额。。

是定语从句跟分词短语之间的转换吧。。。 主动用现在分词，被动用过去分词。。。