簡單的說
通常我們在表示動作的持續進行時,也就是進行式,是使用be +Ving的句型,是動詞加上ing.
但本句You are being unfair to your child. 之unfair是形容詞,不是動詞,無法套用上列的進行式句型來表達,故再使用1個be 動詞來表達進行式(形容詞前都有be動詞,將unfair 前應有的be動詞改being,表達動作的持續進行後,再後置於are之後來完成整句狀態的表達)。
(1)You are (unfair to your child)
=complement to linking v.
=SVO
(2)You are (a bad father), being unfair to your child.
=are being
=verb group include+indicate non-finite cl.,tense-modality,passive, past participial;
#A1. You [are(助動詞) being(現在分詞)] unfair(形容詞) to your child. ←← 現在進行式。
#B1. You [are(be動詞)] unfair(形容詞) to your child. ←← 現在式。
#A2. We [are being] [followed(過去分詞)]. ←← 現在進行式+被動。