1·Note that adjectives, not adverbs, are used after copular verbs. We do not say.
注意联系动词后面接的是形容词，不是副词。不能够说。
2·It is generally accepted that Shi evolved from a pronoun to a assertive copular and to a focus marker.
“是”从代词演变为断定系词，进而成为焦点标记，是语法界普遍接受的事实。