Is( )necessary to tell his father everying?it,this,that三个词用哪一个?为什么?又为什么不用另外两个?

it’s necessary for the younger people to visit te elders,wishing them healthy.翻译 it is necessary for you to work Is it necessary to learn grammer It is necessary for sb to It is necessary to do 的例句 Love is necessary to...是啥意思? To keep healthy is necessary.(同义句) 关于necessary.it is necessary to do sth.it is nec关于necessary. it is necessary to do sth. it is necessary to doing sth. 两者有什么区别?什么时候用to do .什么时候用 to doing?请回答, 英语necessary的问题It is necessary for us to learn.可不可以改成We are necessary to learn The indoor swimming pool seems to be a great deal more luxurious than ( )A is necessary ;B being necessary ;C to be necessary ;D it is necessary is it necessary to tell his father everything?此句用is that necessary Change is not necessary to life,it is life it is clear that sleeping is necessary to everyone It is necessary to protect trees from the frost.翻译 It is necessary to protect trees from the frost. It is necessary ( ) travellers to take a map when is it necessary to pass cet4 or cet6 in uiniversity li is necessary for us to learn English well now.