We'll start at 5 p. m. if it has stopped raining by then.

　　我們五點鐘動身，如果那時雨停了話。

　　We'll start at nine if it has stopped raining by that time.

　　到那時要是雨停了，我們將在9點鐘出發(fā)。

　　We'll start at three o 'clock if it has stopped raining by then.

　　我們將在三點鐘動身，如果那時雨停了的話。