《薄冰高级英语语法》在4.39节认为：Handsome is that handsome does.（做得漂亮才是真漂亮）中的 that引导表语从句。其中的 that 为缩合连接代词，相当于 he or the man who——其实，Handsome is the man whohandsome does 这样的句子仍让人有些费解。个人觉得，对于英语学习者来说，无需过多地作语法分析，只要记住它是一条谚语就行了（有好多汉语中的谚语也不好作过细的语法分析）。在英语中，Handsome is that handsome does.是一条比较常用的谚语，不少名家都常引用它，并且有时还可在is后添加一个逗号。如下面一段摘自狄更斯的《大卫·科波维尔》，其中就引用了Handsome is, that handsome does：

An aunt of my father's, and consequently a great-aunt of mine, ofwhom I shall have more to relate by and by, was the principal magnate of ourfamily. Miss Trotwood, or Miss Betsey, as my poor mother always called her,when she sufficiently overcame her dread of this formidable personage tomention her at all (which was seldom), had been married to a husband youngerthan herself, who was very handsome, except in the sense of the homely adage, “handsome is, thathandsome does”—for he was strongly suspected of having beaten MissBetsey, and even of having once, on a disputed question of supplies, made somehasty but determined arrangements to throw her out of a two pair of stairs'window. These evidences of an incompatibility of temper induced Miss Betsey topay him off, and effect a separation by mutual consent. He went to India with hiscapital, and there, according to a wild legend in our family, he was once seenriding on an elephant, in company with a Baboon; but I think it must have beena Baboo—or a Begum. Anyhow, from India tidings of his death reachedhome, within ten years. How they affected my aunt, nobody knew; for immediatelyupon the separation, she took her maiden name again, bought a cottage in ahamlet on the sea-coast a long way off, established herself there as a singlewoman with one servant, and was understood to live secluded, ever afterwards,in an inflexible retirement.