Global warming quiz

Firstly I have to say that the quiz was so strange, there were different types of questions: obvious ones (that almost everybody must know), logic questions (that maybe you don't know but after thinking them for a minute you can get the correct answer) and finally some questions that I answered luckily. 

I have passed the global warming quiz but I have failed two questions. The third one asked me which planet was the most pollution by the runaway atmosphere gases, the chances were Mars, Earth, Venus and Jupiter. I put the earth because I thought that it was the only planet which have its own atmosphere, but that was wrong, the correct answer was Venus. Then the eleventh question "Hybrid cars get better gas mileage than cars with standard engines" was very confusing in my opinion. The correct answer was "sometimes" but I put always because I didn't know the answer.