what's this in English?It's a pen.为什么不能说是"this is a pen."?详细!this is 在哪能用?二者的区别是什么?谢谢啊!

What’s this in ( ) Fine thanks,And you I'm fine too._________John,what this in English?A:Hello!B:Hi！A:I'm May.what's your name?B:I'm John.Nice to meet you.A:Nice to meet you,too.B:How are you?A:Fine,thanks.And you?B:I'm fine too._____ ______.John,what's this in Engli WHAT'S THIS IN ENGLISH? What`s this in english? What's this in English? What's this in Chinese? What's this in English什么意思 What's this in English?复数 what's this in english表示什么 What's this in English? 是什么意思 what’s this in Chinese?翻译中文 what’s this in English?中文意思 Look!What's this in English?( )(尺子) what's this in english 的答语 同义句 What's this in English? what's this in English的同义词 What's this in English?It's____egg what's this in the backpack