are。the trousers意思是“裤子”，裤子是两条腿的，所以一般用复数形式，谓语也用复数，比如The trousers are a Bit too long for me.但如果是a pair of trousers，谓语就用单数。
the trousers相关例句
The trousers have double thickness knee panels for extra protection.
这条裤子上有双倍厚的护膝片以加强保护。
The trousers have a fly fastening.
这条裤子是前开口。
Drips of water rolled down the trousers of his uniform.
他的制服裤子在不停地滴水。
A wool jacket complements the silk trousers and provides an interesting contrast in texture.
毛料上衣配真丝长裤，质地上的差异非常有趣。
Jeans, the all-purpose denim trousers, have been around for over a hundred years.
牛仔裤，这种适合各种用途的斜纹粗棉布裤子，已经有一百多年历史了。