②This pair of trousers is very new, but Tom’s trousers are very old. (√) [解析] trousers作主语时,谓语动词用复数,但当它被this pair of修饰时谓语动词由pair的单复数确定。因此第②句正确。 特别提醒 this kind of,a piece of,a bag of,a box of等,这类短语...