instruction:
In this task, you are given a paragraph, and your task is to construct a question from the given passage. Construct question in such a way that (i) it is well explained in the paragraph, (ii) the words may/may not be present in the paragraph, (iii) it should start with what/how/describe. Avoid creating a question that (i) is just relevant to one or two sentences, and (ii) not relevant to passage. 
question:
Rain clouds travel across the sky. Rain clouds are stopped or slowed by mountains or wind. The rain clouds drop the rain. The clouds are no longer raining when or if they reach the other side of the obstacle. On the other side of the mountains or rain, there isn't much rain. The area that receives little rain develops a very different ecosystem. The area that receives little rain becomes a desert. 
answer:
How are deserts formed?


question:
Minerals fill spaces between bits of sediment. The sediments become glued together. The glued together parts become hard like cement. The sediment becomes a big rock. The rocks erode slowly. The rocks come apart. The rocks become smaller rocks. The rocks continue to erode into smaller rocks. The process starts again. 
answer:
How does sediment turn into sedimentary rock?


question:
Fuels burns in the combustion chamber. The burning fuel creates energy. The upward motion cause air to be released into the cylinder. The piston compresses the air. A spark ignites the fuel and air inside the cylinder. The pressure pushes the piston down. The exhaust valve opens. The piston pushes the air out of the cylinder. 
answer:

Describe how an internal combustion engine works