1. A counterexample is a specific example or case that contradicts a proposed generalization or theory.
反例是指一个具体的例子或情况，与提出的概括或理论相矛盾。

2. In mathematics, counterexamples are often used to disprove conjectures or to illustrate exceptions to general rules.
在数学中，通常使用反例来证明推测错误或说明一般规则的例外情况。