Something that puzzles; a difficult question or problem.

疑难；难题。

A toy or contrivance designed for testing ingenuity.

测智力的玩具[游戏]。

The state of perplexity.

困惑；迷惑。

To think in perplexity.

苦思；思索。

To perplex.

使迷惑；使困惑。

To solve by reasoning.

解答。