Put on your overcoat, or you will catch cold.

穿大衣，不然会着凉。

He reminded me of what I should otherwise have forgotten.

亏他提醒我, 要不然我就忘了。

Don’t try it on with me, pal, or you’ll be sorry.

伙计，别跟我来这一套，不然会后悔。

You must have been going at a rate of knots to have finished so soon.

肯定干得飞快，不然不会这么早就完成了。

Don't bear hard on the pencil, it will break.

别使劲压铅笔, 不然会断。

He must be teasing,or else he’s mad.

他一定是在开玩笑,不然他就是疯了。

Darling, go now, or you will be late.

亲爱，现在走吧，不然就会迟到了。

Don’t go too far afield or you’ll get lost.

别走得太远, 要不然会迷路。

Lace your boots firmly or the lace will come undone.

把靴子系紧, 不然鞋带会松开。

Make haste, or (else) you'll be late.

快点, 要不然就来不及了。

You must study harder (or) else you'll fail in the English examination.

必须努力学习, 不然话, 英语考试不会及。

Make haste, or we shall miss the train.

快一点, 要不然我们就赶不火车了。

Bill had to support Jill or she would have fallen to the floor.

比尔只得扶住吉尔, 不然她就会摔倒在地。

Use words, not violence, or you’ll just be sinking to their level.

动口，不要动手，不然也堕落到跟他们没什么两样了。

Prices seem to have stopped rising in the shops, or is that just wishful thinking on my part?

商店里东西像不再涨了，要不然就是我一廂情愿？

Jim is irritated enough now; don't blow the coals too much or we shall have an explosion of anger from him.

吉姆现在已经够恼火了, 不要再给他火加油, 不然话, 他会对我们大发脾气。

Your toenails are very long,you ought to cut them before they start growing in,or you could be in a lot of pain.

脚趾甲太长了,应该剪掉,不然趾甲会往里长,给造成很大痛苦。

At others I would find him on the campstool, sitting in his gray sleeping suit and with his cropped dark hair like a patient, unmoved convict.

不然我便见他坐在折凳，穿着灰色睡衣，一头黑发剪得短短，活象一个耐性挺、不动情囚犯。

Don’t mention the Internet in front of him, or he’ll get on his soapbox and we’ll be here all night listening to his opinions about the evils of modern technology.

不要在他面前提因特网，不然他会慷慨陈辞，那我们整晚都要在这儿听他发表关于现代技术种种罪恶高论。