if

Tell me if you get tired of driving and we'll change over.

如果你开车累了,请告诉我,我们可以换一下位置.

We'll never get there if he doesn't speed up.

如果他不快些走,我们一定到不了那里.

If you speed up your work, we can finish before it is dark.

要是你加紧, 我们可以在天黑前结束工作.

If you're wrong, you should admit it.

错了就要认账。

If you find anything wrong with the machine, you should put it right at once.

发现机器有故障, 要及时排除.

I'll help you if possible.

如果可能的话,我会帮助你.

If you live on a mountain , you live off the mountain ; if you live by the water , you live off the water.

靠山吃山, 靠水吃水.

What if we should fail?

倘若我们失败了 怎么办 ?

I doubt whether [ if ] he is at home.

我看他不一定在家.

If I don't go to the party, I shall feel I'm missing out.

如果我不去参加聚会, 我将会感到错失良机.

If plastic and rubber are burnt, they'll give off poisonous gases.

要是塑料和橡胶被焚, 就会放出有毒的气体.

His apparent unwillingness would disappear if we paid him enough.

如果我们付足了钱,他露出的那副不乐意的神情就会消失.

The area can easily be worked out if you know the length and the breadth.

如果你知道长度与宽度,面积很容易计算出来.

I feel suffocated if I don't speak out.

骨鲠在喉,一吐方快.

Litter in the hen coop beds down if it is not raked.

鸡笼里的稻草如不清除会形成硬层.

They were ready to die , if necessary, for their country.

必要时, 他们愿为国捐躯.

If I'd known this beforehand, I would not have gone back.

早知如此, 我就不回去了.

If prices rise the country could slide into anarchy.

如果物价上涨,国家将有可能陷入混乱状态.

The tools will corrode with rust if never used.

这些工具如长期不用会长铁锈而损坏.

If you don't believe what I said, you can go and see for yourself.

如果你不相信我的话, 那你自己去看.

If the new actor is no good, kick him out.

如果那个新来的演员不怎么样就让他走.

They'll catch a packet if they try to go round the points.

如果他们要绕过那个小岬就会有葬身鱼腹的危险.

I will run you in if the bus isn't going into the town because of the snow today.

如果今天公共汽车因为下雪不送你进城的话,我会开车送你去的.

If you close that door, you can shut the noise in.

你要是关上那扇门, 就听不到吵闹声了.

If you tried, you could do the work better.

如果你试试的话, 准能把那项工作干得更好.

If you criticize Pablo, he becomes very abrasive.

如果你批评帕布罗, 他就会变得非常粗暴.

We will not attack unless we are attacked; if we are attacked, we will certainly counterattack.

人不犯我,我不犯人; 人若犯我, 我必犯人.

Why wa ste valuable teaching time trying to knock in a list of facts, if the children aren't interested?

既然孩子们对罗列的事实不感兴趣,为什么要浪费宝贵的教学时间强行塞给他们 呢 ?

I shall have to read up on this subject if I am to give a talk about it.

如果我准备做一次关于这课题的讲座,我就必须把它彻底研究一番.

If anything should happen to him, that would be too bad.

如什么意外的事临到他的头上, 可就糟了.