This is a ruler （

This is "a ruler". This is a ruler(对a ruler提问) ----- -----this? This is a red ruler 用a red ruler 提问 Is this a ruler.(做否定回答) This is a ruler 改为一般疑问句 This is a ruler改为一般疑问句 this is a ruler.改复数 is,a,this,red,ruler 连成句 this is a ruler 改为复数 Whis is this?回答A：This is ruler.B：It is a ruler. ( ) ruler is this? Is this red ruler (