We often play in the ____ ____ ____.
——Don't open the door, _______who knocks on it.——No problem, mom. You've told me many times.
气候变暖导致北极地区海冰减少，也间接导致了严寒，下列哪一项人类活动不会导致气候变暖（ ）
黄土高原的治理措施是（ ）
