[問題]pp-test2-Q13 ( structure ) (已收錄)

[micki]

13. Cotton is grown throughout the world, and _________ year about 50 million bales, weighing nearly 500 pounds apiece, are produced.
A. each
B. a
C. by a
D. in which

A: (A)

請問為何不能用B.a

請問文法上有錯嗎?