连词不是两侧连接要相同成分吗？譬如连接词与词、词组与词组、句子与句子之间，可我感觉下面得句子也对吧？
He is handsome and in good health.
那样问题就来了，这不是连接的词与词组么，到底我哪儿理解错了呢？这个相同成分指的是什么和什么之间呢？
你的理解是对的。你说的这个句子He is handsome and in good health. 正确，and 连接的两个成分是同一个主语，但这两个成分不肯定完全对等，其实是承前省略了is。以下句子都可以说：
He is handsome and he is in good health.
He is handsome and is in good health.
He is handsome andin good health.
又如：
Tom is my best friend and he is good at playing chess.
Tom is my best friend and is good at playing chess.
Tom is my best friend and good at playing chess.
