[单项选择] Questions 57 to 61 are based on the following passage.
The most pressing nuclear energy issue is the disposal of nuclear waste. Even if all the reactors in existence were completely safe to operate, there would still be unsolved issue of what to do with the waste from generating electricity by means of nuclear energy. Those who claim that they feel comfortable with nuclear energy are, none the less, concerned about waste disposal methods. Seven states, including California, have put the building of nuclear plants on hold until legislators are convinced that there is a safe way to dispose of the radioactive waste from the plants.
In the meantime, pools of liquid waste and piles of solid waste from private industry and governmental bomb production grow. Since 1962, the volume of radioactive waste produced by the nuclear power industry has amounted to about 4,300 cubic meters. By the end of the twentieth century, if production continues at the same rate, there wil
A. steam
B. strengthen
C. flow out
D. harden