He spoke through a microphone , ______ he was clearly heard in the great hall

It ______ we had stayed together for a couple of weeks ______ I found we had a lot in common.

The poster was revised _________the suggestions of other group members.

Underground railway is being built in Shenyang. We are sure to take the subway to ______ in the city in no time.

Steel, brick and cement are all necessary building materials _____ [ ]