This is a set( )keys

This is a set( )keys this is换he/she is,a set of keys换keys可以吗? This is my dictionary.(改为一般疑问句 set to that a of is keys room a set of keys is on I lost a set of keys.然后是用 Is this yours?还是Are these yours? 是there is a set of keys还是there are a set of keys? A set of keys A set of keys is in it.变为一般疑问句 here is a set of keys.改为否定句 Here is a set ____ keys横线上填什么? A set of keys is here划线提问 There is ( ) A.key B.a set of key C a set of keys D.keys 选哪个