找出与其他三个不同类的单词。
(    ) 1. A. plane        B. subway          C. comic book
(    ) 2. A. cleaner      B. factory         C. worker
(    ) 3. A. red light    B. traffic light   C. yellow light
(    ) 4. A. ill          B. sad             C. mouse
(    ) 5. A. dancing      B. swimming        C. sing