1.The inessential has become perfectly essential.

无用之物都变成了有用之才。

2.These changes may be inessential, but they are harmless.

的改变也许无关紧要，但却不会招惹麻烦。

3.A sense of smell has long been regarded as something trivial and even inessential to humans (as opposed to other animals, such as dogs, who live by their noses).

长期以来，嗅觉一被认为是人类微不足道的东西，甚至是无关紧要的东西(与其他动物相，狗，它们靠鼻子生活)。

4.I think this kind of thinking, the thinking that senior employment is inessential, is actually the seed of a major problem that could impact a lot of lives, especially the lives of people in developing countries.

我认为，种想法，即认为老年人就业无关紧要，实际上是一个重大问题的根源，尤其影响到发展中国家人民生活。