Hi Mowgli,
Someone else can give you the technical explanation for the exceptions to your teacher's rule. For a native speaker, these are very natural constructions if used in the right place. Here, for instance, is a brief excerpt from a 'walkthrough' of level 13 for the video game Shadow Warrior: (It goes on and on with numerous examples like yours.)
"This level takes place inside an airport. You will use three keys which include the red, yellow, and blue keys. You'll start the level right beside the plane that crashed at the end of the last level. In this room are some telephones and some health on the east side of the room. Go through the door to the south and kill any enemy Ninjas. In the room there is a desk and there is a Ninja crouching behind the desk to be aware of. On the desk is a computer and beside the computer is some health.
Now go through the door to the south and kill any enemies which will include at least one Female Warrior. To the east you will see a doorway to a room that has a bunch of pachinko machines in it. Slowly walk into the room and there will be an explosion as you enter. The explosion will be on the other side of the pachinko which will blow a hole in the wall and into the airplane beyond the wall. Once the explosion has settled, go into the hole to the airplane. On the floor is some health and on the floor in the back of the plane is the red key. On the seat beside the red key is a pair of night vision goggles which you will need later on. Now go back through the hole, the doorway, and back into the room with the desk.
Now unlock the elevator with the red key and push the button on the side of the elevator to activate it. Once you get to the bottom and door opens, kill the Ninja that is on the second floor up above. Now go into the doorway to the west and go up the spiral stairs. Kill the Ninja that is in there to the left of the cash register. Many items are inside the room with the magazine racks and cash register including UZI clips, Shurikens, heat-seeker card, flash bomb, and health. There is also a Riot Gun on the floor beside the cash register but be careful getting it because there are caltrops on the floor you will have to jump over. Also on the second level is a trash can in the corner by the large hole in the floor showing the bottom room. If you shoot the trash can with something explosive then it will blow up and a Guardian Head will pop out and most likely land on the floor in the bottom room."