adversary|adversaries

在棋局中，他遇到了一个强大的对手。

During the chess match, he faced a skilled ___adversary.

在辩论中，他遇到了几位强有力的对手。

In the debate, he faced several strong ___adversaries.

在辩论中，她机智地反驳了对手的每一个论点。

In the debate, she skillfully countered every argument from her ___adversary.