单项选择题
A. has no result yet B. is proved effective C. is welcomed by suicides D. has been refused by stations
A. Candy, soda and popcorn. B. Entertainment, clothing and vacations. C. Sports cars, boats and electronics. D. Food, housing and taxes.
A. it supported life in the past B. certain gases are used to cool the planet C. the atmosphere can be heated enough to grow simple plants D. the planet’s volcanoes become as active as they were in the past