试问，想要做出下图中对称的2只鸟儿，需要哪些工具和命令（）？
A.画布大小
B.矩形选框
C.仿制图章
D.自由变换
参考答案：A, B, D
开动脑筋，用所给单词的正确形式填空。
1. They are four . (tree)
2. This is . (elephant)
3. A cat has fur, and a tail. (paw)
4. The sheep is on the rope. (pull)
5. These are two same . (leaf)
画出BZ-1型直流屏的直流母线电压监察装置接线图。
