falter

The runner's pace began to falter during the last mile of the race as fatigue set in.

(Chinese) 随着疲劳袭来，那名跑者的步调在比赛的最后一英里开始变得踉跄。

Her voice did not falter as she stood before the large crowd and delivered the difficult news.

(Chinese) 当她站在大群观众面前宣布那个不幸的消息时，她的声音没有颤抖。