However, once the ability to record sound was invented, music players_____ underwent a series of rapid changes.

35. Don’t sit _____the corner of the desk.That’s impolite for a student.

It was at 12 o’clock _________ they came home fromschool.

He couldn’t help ____ .The news was so ____.

下列句子中，加线词语使用恰当的一项是 （ ）