阿摩線上測驗
4. According to researchers, there are an estimated 73,300 _______ of tree on Earth, 9,000 of which have yet to be discovered.
(A) species
(B) variations
(C) variants
(D) selections
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統計： A(1), B(0), C(0), D(0), E(0) #3364168
統計： A(1), B(0), C(0), D(0), E(0) #3364168
