A:①②③
B:②③④
C:①②④
D:①③④
You are discussing the following picture with your English friend Jim. Now you are telling him how you understand the picture and what makes you think so.
已知两个五边形相似,其中一个五边形的最长边为20,最短边为4,另一个五边形的最短边为3,则它的最长边为( )
以下地区的山地,垂直自然带分布最复杂的是()
我国地势总的特征是( )