■if 的用法。其意為“如果”：
He抣l do it if you pay him. 如果你付錢(qián)，他是會(huì)干的。
If you ask him, he will help you. 如果你向他提出請(qǐng)求，他會(huì)幫助你。
■unless 的用法。其意為“如果不”、“除非”：
I shall go there tomorrow unless I’m too busy. 如果我不太忙，明天將到那兒去。
Unless you go at once you will be late. 如果你不馬上走，就會(huì)遲到的。
■as [so] long as 的用法。其意為“如果”、“只要”：
As long as you do your best, we抣l be happy. 只要你盡力，我們就滿(mǎn)意了。
You can go out as long as you promise to be back before 8. 如果你保證八點(diǎn)以前回來(lái)，你可以出去
He抣l do it if you pay him. 如果你付錢(qián)，他是會(huì)干的。
If you ask him, he will help you. 如果你向他提出請(qǐng)求，他會(huì)幫助你。
■unless 的用法。其意為“如果不”、“除非”：
I shall go there tomorrow unless I’m too busy. 如果我不太忙，明天將到那兒去。
Unless you go at once you will be late. 如果你不馬上走，就會(huì)遲到的。
■as [so] long as 的用法。其意為“如果”、“只要”：
As long as you do your best, we抣l be happy. 只要你盡力，我們就滿(mǎn)意了。
You can go out as long as you promise to be back before 8. 如果你保證八點(diǎn)以前回來(lái)，你可以出去