：this is a pen ____ is very cheap?请在空白处填一个关系词
问题描述：
：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?
答
which,定语从句中which可做主语,且主语是物体