1) There
isn't anybody (ИЛИ there is nobody) under the
tree.
2) There isn't anybody behind the tree.
3) There isn't anything (ИЛИ there is
nothing) under the table.
4) There isn't anything on the chair.
5) There isn't
anybody at the door.
6) There isn't anything in the box.
7) There aren't any
doctors among my friends.
8) There aren't any trees in front of the house.