It is so difficult to the bottom of the ocean because some parts are very deep.
A. explore
B. know
C. develop
D. observe
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There is widespread concern that the rising unemployment may a threat to social stability.
A. have
B. lead
C. pose
D. cause
After a (an) physical exam, my doctor said I was in good condition except that my blood pressure was a little high.
A. complicated
B. comprehensive
C. common
D. expensive
Some people believe that the earth can enough food to support at least twice its present population.
A. assemble
B. contribute
C. manufacture
D. yield
Sam the gift of imagination from his family, but he lacked the driving power to take action.
A. inherits
B. heritage
C. receives
D. inherited