关闭当前Activity，可以调用Activity提供的______方法 A: close() B: end() C: finish() D: shutoff()

One benefit the author mentions is that the system______. A: uses no electricity B: has a fire-safety shutoff C: does not pollute the air in the house D: pollute the air in house

One benefit the author mentions is that the system ______ A: uses no electricity B: has a fire-safety shutoff C: docs not pollute the air in the house D: requires less insulation in house walls