wh- question 的問題

是2,4文化正確

首先我們要談談直接問句（direct question)與間接問句（indirect question)
所謂直接問句是我們一般的問句，問句非在另一句子中，這種句子會用倒裝法(inversion)，即助動詞，情態動詞等，會在主詞前，如：

Who are you？
Do you know my uncle?

但間接問句即問句是附屬於另一主句，間接問句與其它句子一樣，不用倒裝，即主詞在助動詞，動詞，情態動詞前，如：

I don't know who he is.
Tell me what you want.
Do you know who wants the car?

就因為這樣，所以正確答案是２，４

希望幫到你！

1. I would like to ask when could we find the dog? X
I would like to know when we could find the dog. = indirect question - this is better than no.2

2. I would like to ask when we could find the dog. OK but with full stop not question mark.

3. Do you know when could we find the dog? X
4. Do you know when we could find the dog? correct - nothing needs to be changed.

Only no. 4 is correct as no change is required at all.

2,4是文法結構正確的寫法，不過當中的could則有點怪，跟句子所表達意思有點格格不入的矛盾。

用when...find the dog表示你是想問何時才能找到那隻狗，但could即是can(能不能)的意思，所以不是在問甚麼時間而是暗示如何才能找得到那隻狗。所以這個助動詞也要跟問的問題相配才可以的。

即是我重寫這問題

I would like to ask when we will find the dog.
Do you know when we will find the dog.

Sentence 1 and 3 are both grammatically correct.
But, I think sentence 3 is better.