what is this ?It is a pen而不是It is pen.但为什么what's this? It's

what is this ?It is a pen而不是It is pen.但为什么what's this? It's What's this?——___.(①It's a pen.②This is pen.③This is an pen. what is this in English?It is a pen而不是It is a pen(英语) what's this in English?It's a pen.为什么不能说是"this is a pen."?详细 What's this It's pen .为什么答句不用this is pen,到底it,that ,this 的用法 What is this 是This is a pen.还是.It is a pen?为什么? --It's a ball pen,( --It's a pencil.A.what is this B.and wha what color is this pen的回答可不可以是It's a red pen It"s my pencil case.What"s in it?Look,this is a pen. what's_?__a pen ?a 、this;this is b 、this;it's c 、 that;that' What's color is the map?\ This's red pen.\ It's a orange jac what's this?It's a pen.为什么不能说是"this is a pen.我们老师说就是不能说this