过去完成时填空-The sun -------------- (rise) when we got there.

when we got there是一个短暂性动作,所以主句的太阳应该是已经升起了,选had risen是对的. was rising是延续性的动作,跟when we got there不太搭配.当然你也可以说was rising.只是跟had risen比,不太符合欧洲人的语法习惯而已.