Until only recently did hydroelectric power was universally considered as an environmentally safe and clean means of electricity generator.
举一反三
- Electricity generated from hydroelectric dams and wind power is more _______ than fossil fuel generated power.
- Hydroelectric power plants generate in a much cleaner way than coal-fired ones. A: electric B: electricity C: electronic D: economic
- My parents are greatly concerned about my ____________ (safe). Not until I got home ___________ (safe) did they feel ____________(relieve).
- Not until recently did people in our village begin to know something about Internet.
- 9% of the world's electricity supply is provided by hydroelectric power.