改变汽车的质量和速度，都能使汽车的动能发生变化，使汽车的质量变为原来的1/2倍、速度变为原来的2倍时，其动能是原来的________倍

Compared with his sister, Jerry is even more ______ to, and more easily troubled by, emotional and

relationship problems. [ ]

A. sceptical

B. addicted

C. available

D. sensitive