Only when _________ the tea-house _______ it was the same place he’d been in last year. [ ]

A. did he reach; he realized      

B. he reached; he realized

C. he reached; did he realize    

D. did he reach; did he realize

    以创新地为中心，向周围地域连续扩散，随着距离的增加，扩散强度逐渐减弱。这种技术的地域扩散形式为[ ]

A、近邻扩散

B、等级扩散

C、位移扩散

D、空间扩散