The Sahara Desert begins at the Atlantic Ocean and extends to the Red Sea.
When you compress something you are pushing it into a smaller space. When something contracts, it gets smaller. An example of contraction is when the volume of a mass of water gets smaller as it cools.
Irony: "I've got more faith in Hitler than in anyone else. ... Elie means that Hitler has kept his promise of killing off all the Jews, while God has not kept any of his to help.
Each guide was helpful, but we forgot to thank them.
You should use the plural pronoun, because we don't know whether the guides were only males, or females, or whether there were both sexes.