当他听到巨响时，全身肌肉都绷紧了。

His muscles ___tensed up when he heard the loud noise.

她在举重前绷紧了手臂肌肉。

She was ___tensing her arm muscles before lifting the weights.

老师的突然提问让整个教室的学生都紧张起来。

The teacher's sudden question ___tensed up all the students in the classroom.