There ____ a full bin yesterday. But there is an empty one now.
人闲桂花落,夜静春山空。
月出惊山鸟,时鸣春涧中。
一个三角形和一个平行四边形的面积相等,底也相等,三角形高是4厘米,则平行四边形的高是____分米.