bullet : 含义广泛，指各种枪用的子弹。
- bullet wounds
- There were bullet holes in the door.
- He was killed by a bullet in the head.
- A bullet had lodged in the boy's leg.
- a bullet point
项目符号（通常为小黑圆点）（同 bullet point）
shell : 指发射后会爆炸的炮弹。
- If the shell had hit the boat, it would have blown it to pieces.
- Artillery and mortar shells were landing in the outskirts of the city.
- The men were suffering from shell shock.