You can refer to something's bulk when you want to emphasize that it is very large.
The truck pulled out of the lot, its bulk unnerving against the dawn.
卡车驶出停车场,庞大的车身在黎明时分看起来有点儿可怕。
You can refer to a large person's body or to their weight or size as their bulk.
Bannol lowered his bulk carefully into the chair.
班诺尔小心翼翼地将他那肥硕的身躯落座到了椅子上。
bulks , bulking , bulked
bulk up
If someone bulks up or if they bulk up their body, they put on weight in the form of extra muscle.
They feel I need to bulk up, and to improve my upper body strength.
他们觉得我需要变粗壮些,并增强上身的力量。
My friend is obsessed with going to the gym and has really bulked up her arms.
我朋友迷上了去健身房,她确实把胳膊练得粗壮了。
in bulk
If you buy or sell something in bulk, you buy or sell it in large quantities.
Buying in bulk is more economical than shopping for small quantities.
大批采购比少量购买更经济实惠。
The bulk is most of something.
They come from all over the world, though the bulk is from the Indian subcontinent.
他们来自世界各地,但其中大部分人还是来自印度次大陆。
The bulk of something is most of it.
The bulk of the text is essentially a review of these original documents.
文章的大部分基本上是对这些原始文献的回顾。
The vast bulk of imports and exports are carried by sea.
大部分的进出口商品都是通过海路运输的。