句子改错，我觉得是 designed for fighting, 不知是否正确，谢谢解答!
The body structure that developed in birds over millions of years is well designed for fight, being both lightly in weight and remarkably strong.
这是托福语法改错题。一般这种改错题不会是词语错误而是语法错误。原题如下，题中原为flight而不是fight，可能是网友上传时打字失误。being的表语应为形容词而不可以是副词，故lightly是错误之处，应改为形容词light。
The body structure that developed in birds over millions of years is well designed for
flight, being both lightly in weight and remarkably strong.