Make common cause with

• A. I need to figure out how to fit the piano and the bookshelf in this room.
• B. Environment protesters have parted ways with the local people to stop the establishment of the factory.
• C. The police were acting on a tip from an informer and caught the gang red-handed.
• D. The crowd backed away when the man pulled out a knife and most of them cried for help.
• E. You should always back up important files and documents so that you don't lose all your work if something goes wrong.