When students understand the categorization of nouns, and then let students study. The rule change last names counted as plural singular comment from 7 in the knowledge of it.
When students understand the classification of nouns, the students study. Rules for countable nouns from singular to plural noun clause 7 in such knowledge.
When the students to understand the classification of nouns and make students study. The rule changes from the singular is countable plural 7 items in the leaves of such knowledge.