Put on your overcoat, or you will catch cold.

穿上你大衣，不然你会着凉。

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，不然你会后悔。

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

你肯定干得飞快，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.

他一定是笑,不然他就是疯了。

Darling, go now, or you will be late.

亲爱，现走吧，不然你就会迟到了。

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

别走得太远, 要不然你会迷路。

Lace your boots firmly or the lace will come undone.

把你靴子系紧, 不然鞋带会松。

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.

你必须努力学习, 不然, 英语考试不会及格。

Make haste, or we shall miss the train.

快一点, 要不然我们就赶不上火车了。

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

比尔只得扶住吉尔, 不然她就会摔倒地。

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

动口，不要动手，不然你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?

商店里东西价格好像不再上涨了，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.

吉姆现已经够恼火了, 不要再给他火上加油, 不然, 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.

你脚趾甲太长了,应该剪掉,不然趾甲会往里长,给你造成很大痛苦。

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.

不然我便见他坐折凳上，穿着灰色睡衣，一头黑发剪得短短，活象一个耐性挺好、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.

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