英语高手进,帮忙区分两个词的用法.employ和hire以及in advance和in ahead 的区别,

employ
及物动词 vt.
1.雇用[(+as)][O2]
The mill employs a thousand workers.
这家工厂雇用了一千名工人.
2.使用,利用
How do you employ your spare time?
你是怎样利用你的空余时间的?
3.(常与oneself连用或用被动语态)使忙于,使从事于[(+in)]
The children were employed in painting.
孩子们忙于画画儿.
The children employed themselves in painting.
孩子们忙于画画儿.
名词 n.
1.雇用;使用[U]
hire
及物动词 vt.
1.租,租借
They hired a big hall.
他们租了一间大厅.
2.雇,雇用
We hired a driver to take us on a tour of the city.
我们雇用了一个司机带我们游览这个城市.
名词 n.[U]
1.租用,雇用
These cars are for hire.
这些车子供租用.
2.租金;工钱
in advance
1.在前面
The guard of honor marched in advance.
仪仗队走在前面.
2.预先,提前
I ought to have told you in advance.
我应该事先告诉你.
ahead
副词 ad.
1.在前;向前
The hills ahead are not wooded.
前面的山上没有生长树木.
2.预先,事前
You'd better plan ahead.
你最好事先计划一下.
3.领先,占先
Two people were ahead of us,and travelling fast.
有两个人在我们前面,走得很快.
4.多赚,赢得
ahead在指“在前”时,是表达了将来的一个时间,未发生的,指“以后”.