=>

71. We are looking for a cheap, clean, effective source of energy that doesn't cause pollution or waste natural resources.

-> look for: tìm kiếm

72. At present, most of our electricity comes from the use of coal, gas, oil or nuclear power.

-> come from: đến từ

73. This power could be provided by the sun.

-> bị động could be V3/ed

74. One percent of the solar energy that reaches the earth is enough to provide power for the total population.

->be enough to V: đủ để

75. Many countries are already using solar energy.

-> thì HTTD (be Ving)