C 和 D 都是 ,and instead/rather. 这里 ,and 有两种用法:
1) 是 作平行并列.....apples, oranges, and pears.
2) 两个主句 i like apples, and she likes grapes.
这里 c,d 都没有上述两种情况,og 解释 rather/instead to come does not complete the second part of the sentence idiomatically, 估计也是这个意思