if （it is） necessary是什么现象,假设都可以省略?

if it is necessary /if necessary /when it is necessary 意思一样吗 if （it is） necessary是什么现象,假设都可以省略? I will take my laptop with me to the meeting_____这里用if necessary为什么不用if necessary it is Is it necessary and if so,what should be included?求前半句英文的中文翻译. 九年级英语上册9. The doctor will stay up all night to do an operation on you __________. A if it necessary B if you are necessary C if necessary D if is necessar 介词能和副词连用吗?If it is necessary,you can call me at anytime.这个句子中的“at”多余吗?为什么?（不要说是语感） when it is necessary 为什么可以变为when necessary? Fill in each blank with the word given and change the form of the word if __答案是necessary .为什么不用it is necessary If he is also that into me.If necessary是什么意思 we havent settled the problem 什么什么 it is necessary for him to study abroadA,if Bwhere Cwhether Dthat it is necessary that a person do exercises every day if he wishes to be healthya.doesb.do求详解 if you don't want to get into trouble .say no without hesition when it is necessary it is necessary for you to work Is it necessary to learn grammer It is necessary for sb to early 是什么副词It is certainly necessary! It is necessary to do 的例句 It is necessary for us to help each other(同义） _________ __________ ________ _________is necessary for us