I wish that I read this book before the seminar. A. had read B. can read C. was reading D. No improvement

The correct answer is A. had read.

The sentence “I wish that I read this book before the seminar” expresses a regret about the past. The speaker wishes that they had read the book before the seminar, but they did not. The verb “read” in the past perfect tense (had read) is used to express this regret.

The other options are incorrect because they do not express regret about the past.

• The verb “can read” is used to express ability. The speaker is not saying that they were unable to read the book before the seminar.
• The verb “was reading” is used to express an action that was in progress at a specific time in the past. The speaker is not saying that they were reading the book at the time of the seminar.
• The option “No improvement” is incorrect because the sentence is already correct.

I hope this explanation is helpful. Please let me know if you have any other questions.