what's in the pencilbox?回答时用There is a pen.还是 It's a pen.并解释为什么.
问题描述：
what's in the pencilbox?回答时用There is a pen.还是 It's a pen.并解释为什么.
答
用It's。是固定搭配。
答
It's a pen. 因为it's是问句的答语
答
It's a pen
what's 是WHAT IS的意思要用It's回答,这是固定搭配
答
用it's，固定搭配.there be句式是表示存在