The old man keeps walking around this street. I think he is new here and now he has trouble ____ (find) his way.
计算:﹣22﹣(﹣2)2=____
专家认为,由于人类的生产活动等原因,预计到2100年全球平均增温4~5 ℃,这对全球环境将产生重大影响。据此回答下面小题: