as引导时间状语从句,主句和从句应用什么时态?

As作连词引导时间状语从句时,着重强调主句和从句中的动作同时发生,并且从句通常放在主句之前.归纳起来有下列两种情况:
1)状语从句的谓语动词是持续性动词,从句时态常用进行时态.
如:①As he Was waiting,he suddenly heard a voice from above……
②As Bethune and the other doctors were climbing the hills,they could see the enemy entering the village in the valley below.
2)状语从句的谓语动词是终止性动词,从句时态常用一般时态.
如:①As she stood there,she heard the first bell.
②As they looked up,they saw another cloud coming towards them.
③As they watched.it came nearer and nearer.有没有 as的主句和从句都用 进行时的句子？没有