Is this the factory _____ we visited last week?

Is this the factory _____ we visited last week? This is the factory where we visited last week. This factory is ______ the one we visited last week.正确答案是the is this factory that we visited last week,为什么在that 前加the one Is this factory (the one)I visited last week . Is this factory ______you visited last week? is this the Computer center _____ you visited last week? 定语从句(1)Is this factory _______ we visited last week?(2)Is th Is this factory _____ you visited last week?A:Which B:that C ① Is this the factory ______ you visited last week① Is this This is the factory ——you visited last week 和 this is factor Is the factory --------we visited last year