— The iPhone 4s has been on the market for some time. Have you got one?

— Yes, I________one during my visit to Hong Kong. [    ]

A. have bought       

B. bought

C. had bought       

D. would buy

起重机械安全规程要求：跨度等于或超过40m的装卸桥和门式起重机，应装( )。

A．上升极限位置限制器

B．运行极限位置限制器

C．偏斜调整和显示装置

D．缓冲器