Room 8: Getting to the other side!

Push the spike two spaces up, take the apples, then push the spike one to the right. Push the black box on the conveyor belt opposite to the hole and the spike on the same one.

 

Then step on the conveyor belt left to the spike, push the spike one to the right and the black box one up. The spike will save you against the laser and the black box will fill the hole.

Now, the option is your, you can go to room to the left, or to the one to the right

When you have got both keys, open the two yellow doors, and go for the dark room above