Of the blood that has to be destroyed, almost half is caused by the presence of Hepatitis B, Hepatitis C,and syphilis, while the other half is due to problems in the collection process.

VOA: standard.2010.06.04

Right. A is 2; B is 1, and yet somehow the process gets undone.

对的，A是2，B是，但是不知为何那个处理没有完成。

哈佛公开课 - 计算机科学课程节选