我想知道"trouble"的意思

英语书上说"trouble"是名词,但又有"be trouble"的用法，"be ”后面不应该跟形容词或动词的"ing"形式吗？"trouble"到底应该怎么用？
那"be trouble"应该怎样用?

trouble是名词。
be in trouble

troublesome是形容词

trouble
n.
烦恼, 麻烦, 动乱, 纠纷, 疾病, 故障, 问题
vt.
(使)烦恼, 麻烦, 打扰, 麻烦自己, 费神, 费心

trouble
[5trQb(E)l]
n.
困难；麻烦；着急；危急；烦恼
The boy caused a lot of trouble to his parents；he was always in trouble.
这个男孩给他的父母招来很多麻烦，他甚为苦恼。
Students growing up from nursery school to college have trouble dealing with realities.
从幼儿园到大学的大学生在如何应付现实生活上都存在困难。
困境；被责难的处境；动乱；纠纷
Trouble seems to be developing both in the cities and in the villages.
城市和农村好象都在酝酿着麻烦的事端。
Trouble may flare up in the big cities at any time. (喻)
那些大城市里随时都可能会突然出现麻烦事。
We're in trouble; this is no time for contention.
我们处境很困难,现在不是争论的时候。
过错；罪过
疾病；病痛；生理上的毛病

ask for trouble
找麻烦 (= look for trouble)
get (a girl) into trouble
使（女孩）未婚怀孕

trouble
vt., vi.
-bled, -bling
使焦急；使忧虑；使紧张
麻烦
Can I trouble you to shut the door?