In order to keep the balance of ecosystem, every possible means _______to deal with the problems of the over-exploiting of natural resources. 
#101293
A
has tried
B
has been tried
C
have taken
D
have been taken
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In the past ten years, the ____mountain climber ____ a lot from his own adventurous _______
#102427
A
experienced; experienced; experience
B
experience; experienced; experiences
C
experienced; has experienced; experiences
D
experience; has experience; experience
Helen said that they ________ for 3 years.
#103890
A
had married
B
married
C
had been married
D
had marriage
I ________ up to $5 000 by the time the new term begins in September.
#99453
A
have saved
B
will have saved
C
will be saving
D
had saved