“打呵欠”用英语怎么说

她听讲座时一直在打呵欠.She yawned during the lecture.听得见我打呵欠的声音 么 ?Can you hear my yawn?我上他的课时, 总是竭力地制止自己打呵欠.When I attended his lecture, I always tried hard to strangle yawns....