This can be hard to do especially if you are a long time impulse spender.

这一步很难做到，特别是如果你已是一个长期冲动消费者的情况下。

When you're feeling blue, it can be hard to muster up the physical and mental energy to do the things that make you happier.

当你感觉忧郁时，很难振作精神去做一些让自己开心的事。

Breaking up may actually not be hard to do, say scientists who've found a population of tropical butterflies that may be on its way to a split into two distinct species.

实际上种群的分裂也许并不难做到，科学家说他们已经发现：一种热带的蝴蝶种群也许正是靠着这样的模式变成了两个独特的种群。