18. For over a decade, U.S. military and counterterrorism officials have warned that Africa was poised
to become the next frontier _____ international terrorist organizations.
(A) out
(B) for
(C) on
(D) at
詳解 (共 4 筆)
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翻譯 : 十多年來,美國軍方和反恐官員一...
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跟frontier沒關係喔 同樣結構, ...
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frontier for(邊界) .....
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來自紐約時報 https://www.n...