I know that you came to my class only once on the first day and that you have been absent from all the others. Yet I have found only one small mistake in your paper. （ ） is that?
How is that?= How it can be happened by one time attendance to complete the paper without significant mistake. 比较理性讨论不上课还能近乎完美做好论文; Why is that = Who helped you to finish the paper? 直接问为什么抄袭他人论文，是谁提供的?