单选题 The sixth generation computers with artificial intelligence ______ and perfected now.
A. developed B. will have been developed
C. have developed D. are being developed

【正确答案】 D
【答案解析】[解析] 四个选项都是动词谓语形式，都有develop一词，据此可断定develop为谓语动词。题中主句主语为computer，计算机应是被开发，因此排除主动式，即A和C。B和D区别在于时态。根据题中now一词，即可得出正确选项D。题意：具有人工智能的第六代计算机现在正在被开发和完善。