这是一个有表语从句和定语从句构成的复合句:
表语从句中,主语是:The reason
谓语是:is
表语是:that in the 18th centrury,the uk was a country whose industrial products were ……
其中,表语的引导词是 :that
表语中 有一个定语从句:whose industrial products were.先行词是:country