The intern joined a ride-along in the ambulance to learn about emergency medical procedures.

ride-along 是由动词 ride（乘坐）和副词 along（一起）组成的复合名词，指"陪同出行"或"随行观察"的活动。在医疗急救领域特指实习生跟随救护车出诊的学习方式。