A stitch in time saves nine. 小洞及时补，免得吃大苦。 A watched pot never boils. 心急水不开。 A rolling stone gathers no moss. 滚石不生苔。 A chain is only as strong as its weakest link. 链条的强度取决于最薄弱的一环。 A friend in need is a friend indeed. 患难见真情。 A little knowledge is a dangerous thing. 一知半解可能误事。