选D .句子结构本应是Is this university ________you paid a visit to last year
还原为陈述句This university is ________you paid a visit to last year.
那么定语从句you paid a visit to last year .可以看成是you paid a visit to the university last year.
将the university 提前,即为the university (that /which ) you paid a visit to last year .因为前面主语为the university ,为避免重复,就用the one 来代替the university 做先行词.
又因为the university 在定语从句you paid a visit to the university last year中充当介词to 的宾语,所以关系代词that/which可以被省略掉.因此,句子就是This university is the one (that /which) you paid a visit to last year.变为一般疑问句
Is this universitythe one (that /which) you paid a visit to last year
如果原句为 ：Is this the university ________you paid a visit to last year
还原为陈述句：This is the university _________you paid a visit to last year .那么先行词就是the university .就可选择that或是which 或是省略关系代词都可以.