15. The greenhouse effect is the slow rise of the earth’s ______________ because of the increase in carbon dioxide in the atmosphere.
A. climate
B. energy
C. power
D. temperature
16. Robots can’t get lost. They can ______________ through any environment.
A. complete
B. rescue
C. navigate
D. charge
17. Jack: Don’t you think having a robot do all the housework is a good idea?
Ben: ______________
A. Yes, I don’t think so.
B. No. My children will be lazy then.
C. Yes. It’s not a good idea.
D. Yes, of course. It’s too expensive for my family.
