你可以给一个因饥饿而打哈欠的可怜孩子一个便士吗？
Will you be kind enough to give a penny to a poor boy who is yawning from hunger?
而打哈欠就是其中一部分。
如果这个理论是正确的，那么吸入含有额外二氧化碳的空气应该会引起打哈欠，而吸入纯氧应该可以抑制打哈欠。
If the theory was correct, breathing air with extra carbon dioxide should have triggered yawning, while breathing pure oxygen should have suppressed yawning.
应用推荐