句子成分It is usually most convenient to concentrati ...? it is usually most convenient to concentration at which the adsorbate is found in the process stream to be purified it作为形式主语,代替the adsorbate is found ,is就是谓语,usually most convenient 是宾语,concentration at which the adsorbate is found 是宾语补足语,which the adsorbate is found 是一个定语从句,the adsorbate is found 是真正的主语,in the process stream to be purified 是状语。 不到之处还请指点!查看更多