5．Water pollution happens when waste things from many areas are thrown into rivers，lakes and seas．
Agriculture
To get more food，farmers use large amounts of chemicals（化学制品）．When the chemicals are not completely used by the plants，they are washed away by the rainwater into rivers，lakes and seas，which pollute both surface water and underground water．
Industry
Factories and industries often release poisonous chemicals into seas，rivers or lakes，which is quite bad for Mother Nature．An example of industrial sea pollution happened in Japan in the 1950s．A local factory had poured waste water with mercury（水银）into the Minamata Bay for 20years．Tuna fish in the bay took in the mercury and people ate the tuna．Many children were born with birth deformities（畸形）．As a result，people lost their，hearing and sight，and thousands of people died in the end．
Sea transportation
When ships transporting oil get damaged on the way，oil spillage（溢出）happens•One major disaster was the Exxon Valdez oil spill．An oil tanker sink off Alaska in 1989and leaked（泄漏）oil into the ocean．To save cost，some ships also poured unwanted oil from their engine rooms into the sea，thus polluting the oceans．
Home activities
If the waste from the washing of clothes and dishes are not treated and poured into the sea，they will do harm to the sea life．Some diseases may also spread．Sometimes，rubbish is dumped into the sea．
37．Farmers Use large amounts of chemicals toA．
A．have more food
B．release poison
C．planting
D． plant more crops
38．From the example in Paragraph 3．we learn thatD．
A．eating tuna fish is sometimes a great danger
B．water pollution is a serious problem in Japan
C．factories and industries should be closed in Japan
D．water pollution can do great harm to people's health
39．The underlined word"release"probably meansA．
A．释放
B．吸收
C．生产
D．运用
40．What is the best title for the passage？C
A．Industrial water pollution
B．Agriculture water pollution
C．Reasons for water pollution
D．Ways to solve water pollution．
