[单选题] The outbreak of swine flu that was first detected in Mexico was declared a　global epidemic on June 11, 2009. It is the first worldwide epidemic(　)by the World Health　Organization in 41 years.

A. dripping

B. sealing

C. dropping

D. blocking

A. contribution to solving

B. be contributed to solve

C. contribute to solve

D. be contributed to solving

A. being considered

B. considering

C. to be considered

D. having considered

A. which

B. that

C. who

D. whom

A. forced

B. willing

C. hesitant

D. entitled

选项：A. selected

B. prepared

C. obliged

D. pleased

A. unless

B. until

C. if

D. because

A. breaks

B. warms

C. shows

D. clears