如何区别anyhow 和however?

如何区别anyhow 和however?
为何选anyhow?不选however?
I'm not sure what time I'll arrive,maybe half past seven or a quarter to eight.____ ,I'll be there as early as possible.[ A ]
A．Anyhow B．However
C．Thus D．Therefore

However的用法主要有以下两点：
（一）用作连接副词,相当于no matter how,引导让步状语从句,意思是“不管怎样……”“无论如何……”,具体结构有以下两种：
1．however+形容词+主语+系动词,例：
However rich people are,they always seem anxious to take more money.
无论人们有多富裕,他们似乎总是渴望挣到更多的钱.
2．however+副词+主语+谓语,例：
However fast he runs,he can’t catch up with us.无论他跑得多快也不能赶上我们.
（二）用作连词,引导让步状语从句,意思是“怎么样都行”.例：
In one’s own home one can acts however he wishes.在自己家里一个人想干什么都行.
Whatever的用法主要有以下两点：
（一）引导名词性从句,相当于anything that,意思是“所……的任何事情”,在语气上比what更加强调.例：
Whatever she did was right.她所做的一切都是对的.
Take whatever you want.你想要什么就拿什么吧.
（二）引导让步状语从句,相当于no matter what,意思是“无论什么”,“不管什么”,whatever在从句中可作主语、宾语、表语或定语.例：
Whatever happens,you mustn’t lose your heart.
无论发生什么事情,你都不要丧失信心.
Whatever you do,do it well.
无论你做什么事情都要把它做好.
Whatever I am,it is useful to know foreign languages.
无论我干什么,懂几门外语总是有用的.
You have to go on whatever difficulties you meet.
不管遇到什么困难你都得进行下去.
让我们再来看看前面所提到的那三道高考题.1-3题的答案分别为D、B、C,很明显,第1小题和第3小题考查however引导让步状语从句的用法；第2小题考查whatever引导宾语从句的用法.
anyhow
[5enihau]
adv.
不管怎样,无论如何,反正
不论用什么方法
随随便便
Anyhow I don't like it.
不管怎样我不喜欢它.
You won't be late anyhow.
你无论如何决不会迟到.
Anyhow you can try.
好歹你可试试看.
I could not get in anyhow.
我无论怎样也进不去.
I was in such a hurry that I put my clothes on anyhow.
我很匆忙,所以随便地把衣服穿上了.