6. Helen's mother was recovering at the hospital when she suffered a second fatal attack
(A) when she suffered a second fatal attack
(B) but then suffered a second fatal attack
(C) when she suffered a second and fatal attack
(D) and then suffered a second fatal attack
(E) when a second fatal attack was suffered
想要請教各位~ (A)和(C)選的差別在那裡. (B)不能選的原因是因為but是連接詞, 動詞和前面動詞時態(ing)最好一樣是嗎? 感謝囉~~