Such animals as South China tigers are b

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问题 Such animals as South China tigers are believed __________ ., for we've had no track of them for ages.

选项 A.becoming extinctB.to become extinctC.to have been extinctD.having been extinct

答案C

解析考查时态和语态。当believe为被动语态时,后面习惯接不定式。根据后半句“for we’ve had no track ofthem for ages”判断,时态应为现在完成时,extinct“绝种的,灭绝的”。故选C。
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