问题补充：
Which of the following underlined parts is different in pronunciation from others?
A. The host usually speaks first at a meeting.
B. Please pay attention to the missing part.
C. The old are free to take a bus when it is not the rushing hour.
D. Oh, how windy! Close the window, please.
答案：
A. The host usually speaks first at a meeting.
(答案→)B. Please pay attention to the missing part.
C. The old are free to take a bus when it is not the rushing hour.
D. Oh, how windy! Close the window, please.
解析：句意：。下列哪一个划线部分发音与其他的不同？元音字母o在单词host、old、close中都发字母o的音，所以选B。
