中流砥柱 [- - dǐ zhù]mainstay; a pillar [a firm] rock in midstream; a tower of strength; stand firm as a rock in mid-stream; the chief cornerstone; the solitary rock in a turbulent stream:
•¶ 那五位具有真才实学的工程师是这个小厂的中流砥柱。 The five engineers of real learning are the mainstays of the small factory.