题目

The snow was falling and the roads had become dangerous. The schools were dismissed early, but much to my surprise, my appointment wasn’t canceled. So I went, feeling especially heroic. As far as I could see, I was risking my life to keep my word. Snow or no snow, I would be on time for my scheduled donation at the local blood center.When I got there, I discovered I wasn’t alone. Four more “hero-types” were already lying back in donor chairs with lines attached to their veins (静脉), and machines quietly pumping away to collect their life-saving gifts.Seeing my fellow donors honoring同学们排成排，两个两个地数，数到15次是我；三个三个地数，数到10次也是我，我是个双数，我是第(　　)个人．