奶奶手术后装了心脏起搏器，现在她的心跳正常多了。

After the surgery, grandma had ___pacemakers implanted to help regulate her heartbeat.

在自行车比赛中，领骑选手作为配速员帮助团队保持最佳速度。

In the cycling race, the front rider served as one of the ___pacemakers to help the team maintain an optimal speed.