In the modern age，human society runs on energy．Most machines need electricity to operate．Humans can not live without electricity even a single day both in their daily life and work．They have many different ways to create electricity．But some ways are harmful to the environment．

For example，fossil fuels（化石燃料）are the most common kind of energy．They include coal，oil，and natural gas．First，people have to dig them from the ground．This can sometimes harm the environment．However，scientists are creating cleaner and better ways to do that these days．So the environment is not harmed as much as before．But when people burn these fossil fuels，they can give off a lot of harmful gases，which is considered to be one of the greatest causes of global warming．This might harm the environment．

Tidal（潮汐）energy is another way to make electricity．This uses the ocean tides to make electricity．But some kinds of tidal energy can kill many fish and other sea animals．Also dams（大坝）can create lots of clean energy．But dams create lakes and change the way that rivers run．So they can do great harm to the balance of nature around the lakes and along the rivers．

34．According to the passage，which of the following is TRUE about fossil fuels？___

A．They are dug from the ground．

B．They are considered expensive．

C．They hardly harm the environment．

D．They are not widely used in the world．

35．From the passage，we know that tidal energy can 　　．

A．cause serious accidents                

B．change the way that rivers run   

C．give off a lot of harmful gases       

D．kill many living things in the ocean

36．Nowadays many countries start to use nuclear energy more because 　　．

A．it's a common kind of energy   

B．people ara not afraid of it now   

C．it's cheap，clean and safer than before   

D．people can't live without nuclear energy

37．The passage is probably in the part of 　　in a newspaper．

A．health         

B．science        

C．culture         

D．sports．