[填空题]To separate hydrogen from oxygen needs electricity that can be created by______.

[填空题]To separate hydrogen from oxygen needs electricity that can be created by______.

[填空题]A manager can get the information he needs from ______.

[填空题]Houdini managed to get oxygen from air pockets caught between ______.

[填空题]We must derive hydrogen from renewable sources with a view to a pure hydrogen economy.

[填空题]oxygen

[填空题]The hydrogen can be generated from ____________ or produced by reforming fossil fuels.

[填空题]The hydrogen can be generated from __________________ or produced by reforming fossil fuels.

[填空题]We must derive hydrogen from ____________ with a view to a pure hydrogen economy.

[填空题]We must derive hydrogen from __________________ with a view to a pure hydrogen, economy.

[填空题]
Everyone needs and uses energy. If there were no energy, (46)
Most of the energy on this planet comes from the sun, but people do not receive that energy directly. It comes from different sources and in different forms.
Green plants convert the sun’s energy to food energy that animals and people use for life. The energy from animals has been used for hundreds of years to operate farm equipment and to pull carts, wagons , and other vehicles.
The sun’s energy takes water from rivers, lakes, and oceans and (47) When rain or snow falls on the land some of it flows into rivers and streams. This flowing water can be used to (48) Water can also be converted (更换) to steam, which produces energy to operate machines.
Winds also come from solar energy. Air that has been heated by the sun rises and creates winds. The process of winds has moved ships on the sea, ground grain, and brough