They ____ (plant) trees from 7:00 to 9:00 last Sunday.
环境中影响生物生存的各种因素叫做生态因素.生态因素分为生物因素和非生物因素.影响生物生活的光、水、温度、空气和土壤等属于____因素;影响草原上鹿群生存的狼属于____因素.
The instructions on the bottle are really _______. I can't understand them at all.