“艰难的”用英语怎么说？

超级大国开始着手削减核武器库这项更为艰难的工作。The Superpowers turned to the harder task of cutting their nuclear arsenals.这一年半以来，她度过了一段非常艰难的时期。She's had a really tough time the last year and a half.他正处于非常艰难的时期。He was going through a very...