一片森林里的所有动物、植物和微生物构成一个生态系统.
In the bookshop, a reader asked the shopkeeper __________ Who Moved My Cheese was an interesting book.
钝角三角形的外心在三角形的( )
世界上最高的高原是
若1<x<2,则x-3+x-12的值为( )