A : Doesn't she have any friends?
难道她没有朋友吗？

B : If she has, they mus be fair-weather friends.
如果有，也一定不是不能与她共患难的朋友。

A : Such friends are even worse than enemies.
这样的朋友甚至比敌人还要坏。

B : She'd better keep away from them.
她最好离他们远点儿。

a fair-weather friend
fair-weather本指“鸟亮丽的羽毛”，后用以指人“非常风光”。因此a fair-weather person 指的是a person who stops being a friend when one is in trouble，即“不能共患难的人”。

keep away from：远离......

She had begged him to keep away from cards.
她恳求他不要打牌。 

Keep away from him because he'll bend your ear for hours if given the chance.
别接近他，他一有机会就会缠着你唠唠叨叨地谈上几个钟头。 

I warned her to keep away from that bad set.
我警告过她不要接近那帮坏蛋。
 
They can't keep away from their regular work for long.
他们不能长期离开他们的本职工作。 

had better：最好

I'm not clear about this matter, so I had better keep quiet.
我对这个问题不清楚, 只能不置一词。 

In any case you had better hear what your wife has to say.
总之，你最好听听你妻子的话。