Because modern facilities areemployed in the audio-visual lab,English teachers are required________

本题应选A,给你简单说说：
大意：由于现代化的工具在视听实验（研究）室的应用,英语教师必须（被要求）进行专门的培训.
require 有两种用法：
*require (doing) sth.表示主语“该...了”.
如：
The floor requires washing.
地板该洗了.
*be required to do sth.表示主语必须（被要求）...如：
Students are required to attend classes.
学生必须按规定上课
All passengers are required to show their tickets.
所有乘客都必须出示车票.
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此处是第二种的典型应用.
have (a/some) training 进行培训（训练）.