：this is a pen ____ is very cheap?请在空白处填一个关系词this is a pen ____ is very cheap?请在空白处填一个关系词,我试过很多,感觉都不对,例如 who that 等等.请专业人员帮我解解,到底该填什么?

This is a pen and ____ is a pencil. this is a my pen This is a nice pen. This is a pen.(this)are pencily This pen is mine 保持原句意思 The pen ____ ____ me.This pen is mine 保持原句意思The pen ____ ____ me. This a pen.that is a pen,什么 A:May I help you?B：I bought this pen here,but it is 1.____ 2.____. This is a pen.就划线提问 this is a pen.改为复数句 this is a pen改成一般疑问句 This is a pen.改为一般疑问句 is this a youe pen 怎样改错 This is a nice pen.的问句 This is a pen.(改为复数形式) this is a pen on English.改错 this is red a pen的提问 is this a pen?No it i(). This is a oeange pen对吗?