复数： undesirables
比较级： more undesirable
最高级： most undesirable

The former is undesirable and the latter impossible .

前者是不受欢迎的，后者是不可能的。

Make plans to change undesirable behavior using the skills you 've already learned .

用这些你已经学会的技巧来制定计划去改变这些讨厌的行为。

Critics think this gives the american authorities unjustified powers , for example to boot undesirable websites off the internet .

有评论认为，这给了美国当局不合理的权力，比如他们可以把不合意的网站从网上断开。

Could it still be undesirable ?

这是否仍可能是不受欢迎的？

It would be difficult , and undesirable , to replicate those conditions .

而要在其它地方复制这样的条件则很困难也不受欢迎。