问题: Whatisthemainideaofthelastparagraph?
A: ifferentshapesofrobotsperformdifferentfunctions.
B:Manykindsofrobotshavebeendevelopedtowalkovertrickyterrain.
C:Robots,bigorsmall,performalmostthesamefunction.
D:Noneofthefourkindsofrobotsarestrongenoughtocarrypeoplearound.
