Question

6. As there is less and less coal and oil, scientists are exploring new ways of making use of   energy, such as sunlight, wind and water for power and fuel.

A．primary

B．alternative

C．instant

D．unique

Answer 1

 B

Primary初等的；最初的；alternative可供替代的，可選擇的；instant 立即的，即刻的； unique 單獨一無二的，由常識可知，陽光、風力及水力都是不可能替代能源。