【问】 (a) Could you lend me some money?

(b) Might I have a little brandy?

上面的句子表达的是现在的情况，为什么助动词要用过去时呢?

【答】 在英语里有一种所谓的礼貌过去时(the attitudinal past)：

1. Did you want to see me now?

2. Could I speak to Sue?

3. Could you open the window?

4. Might I have a little brandy?

5. Would you help us?

6. I wondered if you could help me.

7. I was wondering if you could help me.

8. Should I open the window?

9. I wonder if you could look after my child while I am away.

这里使用过去时只是为了表示礼貌，使口气显得委婉、谦逊，而与过去的时间毫不相干。因此在回答中，如果仍保留情态动词的话，一般要换成现在式。句(1)的回答：Yes，I do.句

(2)的回答是：Yes，you can.句(4)的回答是：Yes，you may，句(5)的回答：Yes.I will.