求翻译：幽默教学要时机得当，为教学所需。一是为学生心理所需，即在学生心理疲劳、注意力分散或心情紧张等情况出现时，及时插入幽默；二是为教学内容所需，即在教学内容包含有幽默素材或可用以进行幽默创造时，及时使用和创造幽默。一旦时机得当，整个教学过程就会错落有致，高低起伏。例如：是什么意思？

Humorous teaching to the time properly needed for teaching. First, the psychological need for the students that the student mental fatigue, distraction or nervousness, etc. situation, the timely insertion of humor; second is required for the teaching content, teaching content that contains material