要不的英文：
otherwise
or
or else

参考例句：

I want a soft drinks.
我要不含酒精的的饮料。

I wish you wouldn't chop and change your mind like this; either buy a new motorcycle or don't, but leave me in peace.
我希望你不要这样朝秦暮楚；要不就买辆新摩托车，要不就不买，让我清静一点吧。

We should justify the ardent expectations of our teachers.
我们要不辜负老师的殷切期望。

Don't slink away without apologizing.
不要不道歉就偷偷溜走.

Would you like a fill of my cup of tea?
要不要来一大杯我的茶？

Shall I stick the stamp on the upper right corner of the letter?
要不要把邮票贴在信的右上角

Would you like to take the rest home in a doggy bag?
你要不要把剩菜打包回家?

Would you care to sit down for a while?
你要不要看/坐一会呢?

Will you like to come to a party on Friday evening?
星期五晚上要不要来参加晚会？

Shall I put some anti-freeze in the radiator ?
要不要在散热器里注入一些防冻剂？

otherwise是什么意思：
adv. 否则；另外；在其他方面
adj. 另外的；其他方面的

It did not canned or otherwise preserved.
它没有装罐或者用其他的方法保藏。

If it is not, it will change, otherwise it won't.
如果不对，就可能变。如果是对的，就变不了。

I think he intends otherwise.
我认为他另有打算。

The accident was a blemish in an otherwise perfect evening.
那个意外是那天晚上唯一美中不足的地方。

It was a sad finale to an otherwise spectacular career.
对于一段一直辉煌的职业生涯来说，这是一个惨淡的收官。

else是什么意思：
adv. 其他，另外；否则，要不然

EL usually stands for elevated railway in oral English.
EL在口语中通常代表高价铁道。

.in some gold-mining town called El Dorado in the middle of the amazon
.是在亚马逊河中游的一个叫做黄金国的开采黄金的镇子上拍的

Ernie Els is now the most successful golfer under the age of 30 in the world.
恩尼·埃斯是世界上最成功的30岁以下高尔夫球手。

He laments that people in Villa El Salvador are suspicious of the police.
他哀叹埃尔萨尔瓦多镇的居民居然不信任警方。

While diving in El Gouna, Egypt, I found this little guy.
在埃及的艾高娜潜水的时候，我发现了这个小家伙。