问题
选择题
It has been announced that all the students ____ put on masks before going to school in case they are infected with SARS virus.
A．shall
B．will
C．need
D．may
答案
答案：A
题目分析：考查情态动词：句意：已经宣布所有的学生在上学前要戴面具以防感染SARS病毒，表示：规定或法律条文等用shall 语气强烈，will“意愿”，need“需要”，may“可以”，选A。