什么是系动词 如？

系动词不能单独用作谓语，后边必须跟表语（亦称补语），构成系表结构说明主语的状况、性质、特征等情况。
系动词+adj/doing
be,keep, rest, remain, stay, lie, stand
seem, appear, look,
feel, smell, sound, taste
become, grow, turn, fall, get, go, come, run.

prove, trun out,

be,sound,feel,get,look,taste
系动词+adj