Question

is that it?是什么用法?

原文：He was——in rather low spirits, is that it?

Answer 1

is that it在这句话中相当于一个一般疑问句，也可以写为：Is that he was rather in low spirits so？

Answer 2

He was- in rather low spirits, is that it,

意思是：他情绪很低落，是吧？

He was in rather low spirits, is that it,
这是对： it is that 的反问句。
that 是指： he was in rather low spirits.

Answer 3

He was in rather low spirits, is that it?
is that it是这样吗？用于口语中的。类似于反问。
You don't love me any more, is that it? 你不再爱我啦，是不是这样？
来源：《牛津词典》

Answer 4

He was——in rather low spirits, is that it?的中文意思是：
他是——情绪低落，是吗？

Answer 5

is that it？
就这个吗？
助动词提前

追答

is that it？
就这个吗？
助动词提前