Spoken English slightly differs from country to country. For instance, in some parts of the US the “r” sounds at the end of the words______.

A．is dropped

B．have dropped

C．has dropped

D．are dropped

《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