what is essential is invisible to the eyes这句话是不是有语法错误?总觉得第一个“is"是不是应该删除?一个句子里面怎么能有两个谓语呢?

What bird is essential to eating? What bird is essential to eating? what is essential is invisiable to the eye what is essential is invisible to the eye. What bird is essential to eating?swallow中文是什麼意思 (1/3)From him to reelected,what is essential is not that his policy wor what is your dream?what are essential to realize your dream? It is only with the heart that one can see rightly； what is essential is invisible to the eye. 请问,It is essential to know what you can talk about with different people. It is essential that everyone ___ what to do.A.knowB.knows为什么不是B呢? You should limit your ____(expend)to what is essential.怎么填?为什么?顺便翻译一下, it's only with the heart that one can see rightly,what is essential is invisible to the eye Hard work is essential to success. What kind of table has no legs?What bird is essential to eat?What animal is in every basketballWhat kind of table has no legs?What bird is essential to eat?What animal is in every basketball game?What animal is your girl-friend?What tree is always sa What is becoming essential in the course of economic globalizationg according to the aurthor?怎么翻译啊? 谁给我翻一下这句话?有道的别复制谢谢!Is this tube certified to be compliant with (DIN EN 62776) what is essential for CE. What's the diffents of these two sentences?1.It is essential to follow the .2.It is essetial that you follow the. To make what is said above__,English is essential.A.possible B.it possible C.was possibleD.possibility 请帮我翻译和详细解答好吗?非常感激!