Most of what has been said about the Smiths------(be)also tu

is这里涉及到两个考点1。most of + n。谓语动词是单数还是复数根据后面的名词判断,可数名词后面用复数,不可数名词后面用单数e。g。Most of the students are interested in English。Most of the rice is for the poor。2。本句most of后面是个从句,从句一般属于单数。综合以上,得出is。意思：大多关于史密斯家的言论也适合约翰家。