The correct answer is D. No improvement.
The sentence “I have already read this book twice” is grammatically correct and conveys the intended meaning clearly. The other options are all grammatically incorrect or do not convey the intended meaning as clearly.
Option A, “I already twice have read this book,” is ungrammatical because it uses the past participle “read” as an adjective to modify the noun “book.” The past participle “read” should be used as a verb, as in “I have read this book twice.”
Option B, “I twice have already read this book,” is also ungrammatical because it uses the past participle “read” as an adjective to modify the noun “book.” The past participle “read” should be used as a verb, as in “I have read this book twice.”
Option C, “I have twice already read this book,” is grammatically correct, but it does not convey the intended meaning as clearly as the original sentence. The word “twice” is redundant in this sentence, as the word “already” already indicates that the action has been completed twice.
Therefore, the correct answer is D. No improvement.