题目

Zap, the electric car company ______ in Santa Rosa,California, is adding another electric car to its production plan. A．based                     B．basing               C．to base                     D．bases 答案：A甘薯块根、种子、叶片和茎均可用于繁殖。一甘薯品种为杂合子，为保持该品种的优良特性，不能使用哪种器官繁殖( )A.种子B.块根C.叶片D.茎