The hem is the part where your pants are sewn together, like at the bottom they sew them up, they kind of fold them in half and sew them again.

下摆是你裤子缝在一起的部分，在底部缝起来，他们把它们对折，然后再缝一次。

The key to " cutoffs" is that when you cut off the bottom of the pant leg, you don't sew up the bottom of the shorts, or what are now shorts, to make them look nice.

“剪裁” 的关键在于， 当你剪掉裤腿的底部时，你不会把短裤的底部缝起来，或者现在的短裤，让它们看起来好看。