对以下句子进行语法检查，并指出错误所在。
Even though it was raining, but we still decided to go hiking.
句子中的错误是连词。 "Even though" 表示尽管或虽然，是一个从属连词，因此不需要再添加一个并列连词 "but"。正确的写法是 "Even though it was raining, we still decided to go hiking."