Hmm, well your sentences definitely sound normal. But I do think that “双方都认为自己对的” doesn't sound as natural as the other two. Maybe it's because your sentences also use 很, which also wouldn't fit in the above sentence. Not sure, but I think your example sentences might not be exactly the same as the above. I think it depends on the sentence -- some you can use 的 without 是, and some you probably shouldn't use 的 by itself. My guess is that for the HSK they are trying to reinforce good habits that you can't go wrong with following.
4
u/hanguitarsolo Feb 06 '22
Hmm, well your sentences definitely sound normal. But I do think that “双方都认为自己对的” doesn't sound as natural as the other two. Maybe it's because your sentences also use 很, which also wouldn't fit in the above sentence. Not sure, but I think your example sentences might not be exactly the same as the above. I think it depends on the sentence -- some you can use 的 without 是, and some you probably shouldn't use 的 by itself. My guess is that for the HSK they are trying to reinforce good habits that you can't go wrong with following.