... and gas. The world's coal (44)_______ should last longer but, once used, these can not be (45) _______ It is important, therefore, that we should develop such (46)_______ sources of energy ... findings B. productions C. amounts D. sources 44. A. reserves B. stores C. mines D. contents 45. A. updated B. repeated C. renewed D. produced 46. A. traditional B. alternative C. surprising...