He found himself in a very dangerous situation when climbing in Utah.在犹他州登山时,他发现自己处于非常危险的境地。
= He found himself in a very dangerous situation when (he was) climbing in Utah.
1 in a very dangerous situation是介词短语,作宾语himself的补足语。
2 when climbing in Utah是非谓语动词短语, 作时间状语,相当于一个省略的时间状语从句when he was climbing in Utah,因此when依然是连词,只剩去了主语(因与前面主句的主语he一致)和be动词。
While listening to the teacher, you must make notes. 在听老师讲课的时候,你一定要做笔记。
=While you are listening to the teacher, you must make notes.
供参考。
追问谢谢老师的,先采纳,再仔细学习。谢谢您!