a kind of 和be essential

a kind of 是什么(..,种类...)的意思,It's a kind of food(sports)
1.We often do this kind of exercise.
我们经常做这类练习.
2.Taking a blind man across the street is a kind act.
扶盲人过马路是一种善良的行为.
3.People had told me she was very pleasant but she's nothing of the kind.
人家告诉我她很可爱,可是她根本不是那样.
be essential of 这是一个固定搭配,在不同的句子里有不同的意思.如：1.Food is essential to life.
食物对生命是必不可少的.
2.Her most essential quality is kindness.
她最主要的品质是善良.
3.In considering this problem,you should grasp its essentials.
在考虑这一问题时,你应当抓住实质.