(The metal) aluminum (has been) (first) isolated (early) in the nineteenth centu

游客2025-03-16 4

问题 (The metal) aluminum (has been) (first) isolated (early) in the nineteenth century.

选项 A、The metal
B、has been
C、first
D、early

答案 B

解析应改为was。本句中有具体表示过去的时间状语，所以应该用一般过去时。

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Theagriculturalrevolutioninthenineteenthcenturyinvolvedtwothings:t