Create a compound or complex sentence with the simple ones

1.  I help to conserve natural sites, I save energy,  I recycle glass (compound complex): If  I recycle glass I help to conserve natural sites and I save energy.
2. People prefer using glass to plastic. Glass is cheaper than plastic. (Complex): People prefer using glass to plastic because glass is cheaper than plastic.
3.  Students need to change activities constantly; their concentration spam could last 15 or 20 minutes. (Complex): students need to change activities constantly because their concentration spam could last 15 or 20 minutes. 
4. The teacher prefers the floor to work, the chairs are not appropriate for them (Complex): The teacher prefers the floor to work because the chairs are not appropriate for them.
5. This second game works much better; the students are familiar with the game first (complex): game works much better when the students are familiar with the game first
6. Paula and Carlos ate hot dogs, Alonso drunk a soda: (compound). Paula and Carlos ate hot dogs but Alonso drunk a soda.
7. You were sad, the party was over (Complex): You were sad when the party was over
8. We all have a nice party night, you stayed worried at home. (Complex): We all have a nice party night while you stayed worried at home.
9. Joe waited for the train. The train arrived late. (Complex): The train arrived late, but Joe waited for it
10.  Marie is French, she has a particular accent in English, I don’t understand, she speaks : (compound-complex): Marie has a particular accent in English because she is French, however I don’t understand when she speaks.