It has been announced that students remain in their seats until all the papers have been collected.
A. can
B. will
C. shall
D. may
网友回答
A. can
B. will
(答案→)C. shall
D. may
解析：考查情态动词shall用法。情态动词Shall用于所有人称，表示命令，警告，允诺；以及法律规定中要做的事情。句意：据宣布，所有的学生都要坐在位置上，知道所有的试卷都被收齐。说明本句是根据考生的规定所要做的事情。故C正确。