prey
可以说a prey，但不可说preys，注意下面第一句、第二句和第三句里用a prey，第四句和第五句里用prey，第五句里加上a也可以：
- The bird fell a prey to the cat.
- Two birds fell a prey to the cat.
- He used to be a prey to sleeplessness.
- Birds are the prey of cats.
- In those days colonialists often regarded their slaves as legitimate prey.
