Is this的用法

Is this的用法 this is的用法急不要造句 that is why和 this is why用法的区别 that is it is it is for this is for的区别及用法 this指针的用法 this指针的用法 this的用法 this,that的用法 this is because的用法如果后面是过去式是不是要改为this was because? is this 和this is用法有什么不同? a和an的用法This is( )book This is( )eraser This is( )Englishbook This is( )dictionary This is( )notebook This is( )encyclopdia 在（ ）填a或an This is according to...这种用法对吗? this is not always what happens but it is what should happen特别是what 的用法 This开头和 It is开头用法的区别例；This si a pen和It is a pen This与Here的用法有什么区别么?我要知道具体的用法,比如：This is my umbrella/Here is my umbrella 的区别? this kind of 的用法 is;am用法有何不同.This is; 和This are用法有何不同. this is 与this's 的区别?在哪些情况下有不同的含义或用法?