these trousers 是对的.
还可以说：this pair of trousers
According to the color, I would say that this jacket belongs to those trousers.
按颜色来说呢，我觉得这件夹克和那条裤子很配。
I threw those trousers out years ago.
几年前我就把那些裤子扔掉了。
I bought this pair of trousers two days ago.
我两天前买了这条裤子。
This pair of trousers doesn't fit me.
这条裤子我穿不合适。
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