题目内容：
It never occurred to humans until the mid-1990s __________some animals can be cloned.
参考答案：
答案解析：
单选题：It never occurred to humans until the mid-1990s __________so
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- 题目类型：单选题
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--How do you usually keep in touch with your friends, by ema
--How do you usually keep in touch with your friends, by email or letter?--_____
Greg is an acknowledgeable expert of handling money exchange
Greg is an acknowledgeable expert of handling money exchange. Last year he was l
中国国家质检总局将继续加强对企业的监督管理．要求企业进一步完善其质量安全自控体系，确保出口日本产品质量安全；同时将继续加
中国国家质检总局将继续加强对企业的监督管理．要求企业进一步完善其质量安全自控体系，确保出口日本产品质量安全；同时将继续加强与日方__________。_____
From these examples of adverts, we can conclude that（ ）
From these examples of adverts, we can conclude that（ ）
下列各项中，不需要证人在场即为有效的是（ ）。
下列各项中，不需要证人在场即为有效的是（ ）。