题目

如图，四边形ABCD中，AB=AD，CB=CD，但ADCD，我们称这样的四边形为“半菱形”。小明说“‘半菱形’的面积等于两条对角线乘积的一半”。他的说法正确吗？请你判断并证明你的结论。 答案：假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。删除：把多余的词用斜线（\）划掉。删除：在错的词下划一横线，并在该词下面写出修改后的词。注意：1. 每处错误及其修改均仅限一词；2. 只允许修改 10 处，多者（从第 11 处起）不计分。March 12 is memorable because our class had a meaningful experience in that day. In the morning, we cycled to suburbs to plant trees, talking and laughed all the way. Upon arrival, we began to work hardly. Some were digging holes. Some are carrying and planting young trees. Others were watering it. After getting the work done, we put up a board reminding of people to protect the trees. Before leaving we took some photo to record our green action. Seen the lines of trees, we all had a sense of achievement. We feel it’s our duty to protect or beautify our environment.