至于
As for…; (不至于) not to the point of
HSK 5HSK 3.0 · 5
…，至于 + related topic，… | 不至于 + V | …，至于吗？
至于 shifts to a related but different topic, 'as for': 我只负责买票，至于住的地方，你们自己安排吧. It usually appears in the SECOND sentence or clause, unlike 关于, which introduces a topic at the start. 不至于 means 'not so bad as to': 他不至于不知道吧. Colloquially, 至于吗？ is a rhetorical 'is that really necessary?', criticizing an overreaction.
HSK 5 gap fills; 至于 vs 关于 often appear together.
Examples
我只负责买票，至于住的地方，你们自己安排吧。
I'm only handling tickets; as for accommodation, sort it out yourselves.
他答应来，至于什么时候来，我就不知道了。
He promised to come; as for when, I don't know.
这次考试虽然难，但我不至于不及格。
The exam was hard, but I won't go so far as to fail.
为这点儿小事生气，至于吗？
Getting angry over something so small — is that really necessary?
Exercises
1.这件事我同意了， 具体怎么做，你们商量吧。
2.他只是感冒， 住院吧？
3.“为这点儿小事吵架，至于吗？”的意思是：
4.衣服的颜色我很喜欢， 价格，还可以再商量。