brainteaser

This brainteaser took me an hour to solve.

用法提示：brainteaser 是名词，表示‘脑筋急转弯’，在句中作主语。

The teacher gave the class a brainteaser to warm up our minds.

用法提示：brainteaser 是名词，作直接宾语，指一个测试智力的谜题。

She enjoys doing brainteasers on the train every morning.

用法提示：brainteaser 是名词，此处用复数 brainteasers 作 do 的宾语，表示这类谜题。