be動詞の進行形/受動態(I am being selfish)
New kinds of devices are being developed all the time
ingがp.p.になる代わりにhave/be動詞がing系になる
受動態過去進行形
I am selfish(私は我儘)
I am being selfish(私はいま我儘になってる)
be動詞の現在進行形
It was mentioned (受動態過去形)
It was being mentioned (受動態過去進行形)