When I got home yesterday afternoon, I saw my mother ____ (cook) in the kitchen.
如图所示,找一只一端开口的空纸筒,将开口处蒙上一张气球皮,并将底部钻个约小手指大的洞。
计算:(3+1)((27﹣12﹣1)•cos45°•﹣12011