a.[Z][B]

1. 两者（或若干）中择一的；非此即彼的
2. 替代的；供选择的
   There was no alternative route open to her.

   她别无选择。

3. 不接受世俗准则的；非传统的；非主流的

n.

1. 选择，二择一[the S][（+of）]
   If you don't like the school lunch, you have the alternative of bringing your own.

   要是你不喜欢学校准备的午餐，你可以自己带饭。

2. 供选择的东西（或办法等）[C]
   What alternatives are there?

   还有什么可选择的？

3. 选择的自由（或余地）[U]
   They had no alternative in the matter.

   在这件事上，他们没有选择的余地。

adj.

1. (of one or more things) available as another possibility.
   ▸(of two things) mutually exclusive.
2. relating to activities that depart from or challenge traditional norms.

n.