Other genetic similarities suggested they all ________ a single, common ancestor about 300 years ago.

A．had B．have had C．have D．had had

 

A

【解析】A　考查動詞時態(tài)。suggest在該句中意為“表明，暗示”，而非“建議”，所以賓語從句中不用虛擬語氣。因為賓語從句的時間狀語為about 300 years ago，故該句用一般過去時態(tài)，選A項。

 

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