It has been announced that students _______ remain in their seats until all the papers have been collected
A.canB.mayC.willD.shall在线课程D
本题考查情态动词在这句话中，正确的句意应该为：学生必须留在座位上，直到所有的试卷都被收完为止。shall用作情态动词时，主语可以为第二或者第三人称，表示说话者对主语的命令、要求或者承诺等等，最符合本句的意思。而may/ can表允许；will表意愿，均不符合题意，故排除。