20. VitaminD, which the body needs in order to absorb calcium, is produced when skin is exposed to ultraviolet rays.
(A) calcium, is produced
(B) calcium, and is produced
(C) calcium, producing it
(D) calcium and produces
(E) calcium and produces it

答案：登入後查看
統計： A(51), B(3), C(6), D(4), E(3) #2671420

讀好書說好話行好事做好人

B1 · 2021/06/07

#4783089

中間的which...是補充子句，修飾前面主詞Vitamin D，所以第二個逗點後面是連接前面主詞Vitamin D，題目原本已有主要動詞is produced，所以無需修正。

中間的which...可以省略，意思不變：Vitamin D is produced when skin is exposed to ultraviolet rays.