i have read this book twice now i'm reading it third time

问题描述:

i have read this book twice now i'm reading it third time
i have read this book twice .now i'm reading it ( )
A.a third time.B.the third time

答案是 B
我已经读两遍了 现在读第三遍,序数词前要加定冠词 这是规定~