问答题 For most of human history, the dominant concerns about energy has centered【M1】________on the benefit side.Inadequacy of energy resources of the technologies for harvested,【M2】________converting, hence inconvenience, and constraints on its growth.The 1970’s, then,【M3】________represented a turning excessive energy costs could pose threats on the par with those【M4】________of insufficient supply.It also became upon possible to think that expanding some【M5】________forms of energy supply could create costs exceeding the benefits.The crucialquestion at beginning of the 1990’s is whether the trend that began in the 1970’s【M6】_________will prove to be temporary or permanent.Is the eras of cheap energy really over, 【M7】_________or will a combination of new resources, new technology and changing geopoliticsbring it back? One key determinant of the answer is the staggeringly scale of【M8】_________energy demand brought forth by 100 years of population growth and industrialdemand.Except for the huge pool of oil underly the Middle East, the cheapest oil【M9】_________and gas are already gone.Even if a few more giant oil fields are discovered, they willmake little difference against consumption on today’s scale.Oil and gas will haveto come increasingly, for most country, from deeper in the earth and from【M10】_________imports whose reliability and affordability cannot be guaranteed.《问题》：【M5】