The wind from the window makes the lips bob up and down.

窗外的风吹来，嘴唇上下颤动。

But for the last few minutes you've also been watching a different type of connective tissue bob up and down as I talk — cartilage.

但在刚才的几分钟里你们也看到了另一种结缔组织，它在我讲话时上下跳动，那就是软骨。

And you can also see it in other people as well, as their heads begin sort of bobbing up and down during afternoon meetings.

你也可以在其他人身上看到它，因为他们的头在下午的会议上开始上下摆动。

Will tried to focus on the worksheet, but soon his eyes were closed and his head was bobbing up and down with every bump in the road.

威尔试图把注意力集中在工作表上，但很快他的眼睛就闭上了，他的头随着路上的每一个颠簸而上下摆动。

Trying to answer a question with Hermione next to him, bobbing up and down on the balls of her feet with her hand in the air, was very off-putting, but Harry had a go.

赫敏坐在哈利旁边，踮着脚跳上跳下。她的手又举了起来，在这种情况下，要回答问题是使人困窘的，不过哈利不能不回答。

They can clamp their thighs tight and try to remain seated, or they can bob up and down with the rhythm of the horse, standing in the stirrups as they rise off the saddle.

他们会夹紧大腿并保持坐姿，或者随着马跑动节奏上下起伏，臀部离开马鞍时脚踩马镫站立。