This is a pencil and a pen还是This are a pencil and a pen,

用are

This is a pencil, that is a pen.
或者是 These are a pencil and a pen.

对于this就不能用 are 但是如果你要表示你的这支笔既是铅笔又是钢笔那么可以用
This is a pencil and pen.

This is a pencil and a pen?
This are a pencil and a pen?

这两句有问题吧!
应该改成
There is a pencil and a pen
或者是
These are a pencil and a pen

这里不能用is也不能用are