但是有几个问题不明白 用英语怎么说呀？

But there are some problems that I don't understand.

表达方法多种多样：
1. But there are still some questions I do not understand.
2. But I still do not understand some questions
3. However, there are some unknown questions exist
4. However, some questions still haven't been solved yet

However,some of the question which I didn't understand
要用来回答的是问题英语中用的是question而用行动来解决的问题英语中用的是problem

But I have trouble in knowing it

But I've gotten some problems