下列各句中，没有语病的一句是（ ）

Who is the tallestboy —It ______ be John. Johnis of medium height.

I’m sorry. I’m late for the musicpresentation. — Why are you so late Thepresentation _______for 10 minutes.

I went along thinking of nothing________,only looking at things around me .[ ]

Everyone can do it because it is very .