原则上说，连系动词后接形容词作表语，不接副词作表语。如：
误：His English is very well. 他的英语很好。(应将 well 改为 good)
误：Be carefully. 小心点。(应将 carefully 改为 careful)
误：The soup tastes nicely. 这汤味道不错。(应将 nicely 改为 nice)
但是，有时连系动词后也可接副词作表语，这主要限于in, on, off, out, away, behind, up, down, over, through, around, round, below, inside, outside 等少数副词小品词以及 here, there, upstairs, downstairs 等少数表示地点或方位的副词：
Is your mother in? 你母亲在家吗？
Everyone is here now. 现在大家都到齐了。
I must be off now. 我现在得走了。
