stumble
那位紧张的候选人在他重要的演讲中开始结巴了。
The nervous candidate began to ___stumble during his important presentation.
紧张的新星在表演时开始结巴，说不顺台词。
The nervous new star began to ___stumble over her lines during the performance.
即使经验丰富的演员在巨大压力下也可能在台词上出错。
Even experienced actors can ___stumble on their lines when under immense pressure.