Question

Which verb is progressive?

a.
had rung

b.
were ringing

c.
shall ring

d.
will be rung

Answer 1

Will be rung because it's future tense, but shall ring dies not make any sense and it's a command. It's not the rest are not correct because they have no helping verb.

Answer 2

Were ringing is the answer.

That is because it shows that an ongoing action was happening in the past tense form.

Answer: b. were ringing