为什么疑问句既能用some也能用any？

根据剑桥语法，一般规律是：

1、肯定句用some；2、否定句用any；3、疑问句通常用ang，但在希望得到肯定回答的疑问句中用some。

剑桥语法原文如下：

1. Some is most common in affirmative clauses（肯定句）.

例：

• He’s got some homework.
• Not: He’s got any homework.

2. Any is most common in negative clauses（否定句）.

例：

• He hasn’t got any homework.
• Not: He hasn’t got some homework.

3. Any is more common in questions（疑问句） but we can use some when we are expecting the answer to be ‘yes’.

例：

• Has he got any homework?
• Has he got some homework?

注：这两句都正确，但后一句期待的回答是yes，而第一句表明的态度是“事不关已，问问而已”。

原文：https://dictionary.cambridge.org/zhs/语法/英式语法/some-and-any?q=Some+and+any