there must be something in the water There must be something wrong with the engine. There must be something wrong with them. There must be something wrong with the machine. There must be something wrong with the pen he is using. There must be some way to solve this. There must have been a large audience at the concert. There must have been an accident up ahead. There must have been a tacit understanding between them. There must have been some more tea in the pot. There mustn't be any damage or dirt on this product. There must've been a large audience at the concert.