1、under + take.
2、身在其中担任、掌握(take, hold)什么；当然，只有身在其中才能去担任、掌管什么东西了。
3、At here, the under is not the usual word meaning "beneath," but from Old English under, from PIE *enter- "between, among". 另见：understand.
4、undertake => 过去式：undertook.

1. She was secretly vetted before she ever undertook any work for me.

她在为我工作以前曾受到过秘密考查。

来自柯林斯例句

2. He undertook to edit the text himself.

他答应亲自编辑正文的内容。

来自柯林斯例句

3. The lawyer undertook the case.

该律师承办这个案子.

来自《简明英汉词典》

4. He undertook the leadership of the team.

他担任了这个团队的领导.

来自《简明英汉词典》

5. Next he undertook to pay off the debts.

然后,他负责偿还债务.

来自《简明英汉词典》