I went to a group activity, “Sensitivity Sunday”, which was to make us more ____36____ the problems faced by disabled people. We were asked to “____37____ a disability” for several hours one Sunday. Some members, ____38____, chose to use wheelchairs. Others wore sound-blocking earplugs（耳塞）or blindfolds（眼罩）. Just sitting in the wheelchair was a ____39____ experience. I had never considered before how ____40____ it would be to use one. As soon as I sat down, my ____41____ made the chair begin to roll. Its wheels were not ____42____. Then I wondered where to put my ____43____. It took me quite a while to get the metal footrest into ____44____. I took my first uneasy look at what was to be my only means of ____45____ for several hours. For disabled people, “adopting a wheelchair” is not a temporary（临时的） ____46____. I tried to find a ____47____ position and thought it might be restful, ____48____ kind of nice, to be ____49____ around for a while. Looking around, I ____50____ I would have to handle the thing myself My hands started to ache as I ____51____ the heavy metal wheels. I came to know that controlling the ____52____ of the wheelchair was not going to be a(n) ____53____ task. My wheelchair experiment was soon ____54____. It made a deep impression on me. A few hours of “disability” gave me only a taste of the ____55____, both physical and mental, that disabled people must overcome.

A．operation
B．communication
C． transportation
D．production