2. The discovery of the new vaccine is an important ______ in the fight against COVID-19.
(A) breakthrough
(B) commitment
(C) demonstration
(D) interpretation
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統計: A(203), B(14), C(11), D(8), E(0) #2688288
統計: A(203), B(14), C(11), D(8), E(0) #2688288