Listen to the dialog again and answer the following questions.
1. Jack is not very optimistic about high-tech prostheses because
   a. they are too complex to operate.　 b. many people cannot afford them.　 c. their safety has not been guaranteed.　 d. they still have ethical problems to be solved.


2. Yumi refers to mobile phones to show that
   a. they are much cheaper than an artificial leg.　 b. technology develops faster than you imagine.　 c. they are far superior to the conventional telephone.　 d. technology for mobile phones can also be applied to rostheses.