同一个单词可以同时是名词,及物动词,不及物动词,形容词...吗?

基本不可以 或极少,如double
n. 两倍；双精度型
adj. 双重的；两倍的
vi. 加倍,加倍努力；快步走
vt. 使加倍
adv. 双重地；两倍地；弓身地
可不加考虑

罕见， 但有的。一个例子是 hush
名词： There was a hush in the room as the teacher walked in.
形容词： He was paid hush money to keep quiet about the matter.
及物动词：The money did the trick; it hushed him up.
不及物动词: Everyone hushed up as the teacher entered the room.