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I wonder if you have heard the term 'green dam'.
I think it means the water-reserving forest in place
of the artificial concrete dam.

Thank you.
Comments  
This is not a phrase I am familiar with (AmE).
"Green" in this context means "environmentally friendly".

A dam that doesn't damage the environment could be called a "green dam".
Students: We have free audio pronunciation exercises.
It's a chinese web filtering software that filters any sites the Chinese government don't want you to see.
Hi,
Thank you for the information.

'Software' is an uncountable noun.
Say
It's Chinese web filtering software that . . . 
or
It's a piece of Chinese web filtering software that . . .

Best wishes, Clive
Hi,
Thank you for the information.

'Software' is an uncountable noun.
Say
It's Chinese web filtering software that . . . 
or
It's a piece of Chinese web filtering software that . . .

Best wishes, Clive
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It is software to censor the web in china.