"Topic-comment" structure Can someone help me with these? I don't quite understand the topic-comment structure, and I have been trying to look it up but I can't find any good explanation with examples.

I have to change the following sentences so that they reflect the “topic-comment” structure. Can someone help me with these or just explain and send me on the right track?

Thanks in advance!

3.1 你复习昨天的语法了吗？

3.2 你买飞机票了吗？

3.3 你们都喜欢喝中国茶吗？

3.4 瑞典人都喜欢去日本吗？ 

3.5 你不习惯这儿的天气吗？
In short, the topic-comment structure puts the topic you want to focus on in the beginning of a sentence, optionally followed by a comma, and the comment you want to make about the topic right after.
As Dejavision has mentioned, in all of your examples, the topic can be the object. (see note below) Thus, moving the object to the beginning would change the structure to topic-comment.

昨天的语法，你复习了吗？
飞机票，你买了吗？
中国茶，你们都喜欢喝吗？
日本，瑞典人都喜欢去吗？
这儿的天气，你不习惯吗？

Note

This trick does not always apply. The topic can surely be a subject as well.

Consider the following example:

這隻筆，顏色很好看。
As for this pen, the color is good-looking.

這隻筆 is both the subject and the topic.

Depending on the context, the same sentence may have more than one potential topic.

Consider the following example with possible context in parentheses:

（我知道美国大家都喜欢去。至于）日本，瑞典人都喜欢去吗？
(I know that everyone likes going to the States.) As for Japan, do all Swedish like going there?

and

（我知道很多亚洲人喜欢去日本。至于）瑞典人，都喜欢去日本吗？
(I know that many Asians like going to Japan.) As for Swedish, do all of them like going to Japan?

The two questions have different topics, thus different context, but are asking the same thing.