[jack]

Thanks for the detailed explanation.

9. (an) same idea
=> 'an' is non-specific. It means, 'any', whereas 'same' is specific, so use either one or the other, not both: 'an idea' or 'the same idea'. Note, 'the same' is a set pair.

1. Thanks. I use 'the same idea' becuase they're the same and specific?

9. (an) same idea

2. Why isn't it '(a) same idea'? Why is it 'an'?

4. This bird imitates other birds call. (Odd. a plural noun is acting as an adjective)

I don't really understand this one. So this one could be right? It can be 'birds' because the word function as a noun?

So what do these mean then?
3. This bird imitates other birds call.
4. This bird imitates other bird call.

5. The bird imitates other call. (If 'call' is incorrect, is it because 'other' means 'different'? So that means more than on? Could you explain this to me? I don't think my explanation make any sense. Thanks.)
6. the bird imitates other calls.