答案为D、省略了在定语从句中作visited宾语的that或者which,即:visit the factory
解题方法:
1、看定语从句的句子是否完整,完整就用when、why、where关系副词作状语
如果不完整就用who、whom、that、which等作主语、宾语、表语
2、看定语从句的谓语动词,如果是及物动词一般要加一个宾语,即例题的visit+宾语,
如果定语从句的谓语动词是不及物动词,不需要加宾语,一般用关系副词
this is the factory ___we worked a year ago .A.where B that C which D.on which
就像这个句子中的work,是不及物动词,只能说work in the factory,不能说work the factory
所以选where=in which,D错在on