Fill in the blank with the most appropriate word.
I haven't been to Beijing. I wish I _____ to Beijing.
This sentence employs the second conditional that is used to express imaginary or impossible situations. So, second conditional uses forms of verbs in past tense. In case of second conditional, when 'I wish' is used to talk about regret happened (or failed to happen) in the past and is, therefore, impossible to change, then the expressions 'I wish' is followed by past perfect. Hence, Option A is the correct answer here. Options B and C cannot be used as they use forms of verbs in present tense. Option D cannot be used as it would render the sentence grammatically incorrect.