例句與造句

1. On one end of the arm are some counterweights and on the other is a rotating hub which holds 10 cars.
2. The head of the pole needs to provide a freely rotating hub, and usually incorporates a ball bearing race of some kind.
3. The head contains a safety shield on the user side and a rotating hub which may also be called a head or spool.
4. It's difficult to find rotating hub in a sentence. 用rotating hub造句挺難的