问题补充:
. Will you please keep quiet now? You shouldn’t talk until to.
A. asking
B. having asked
C. to ask
D. asked
答案:
A. asking
B. having asked
C. to ask
(答案→)D. asked
解析:考查状语从句的省略。句意:请你现在保持安静好吗,你不应该说话直到你要求被说。完整形式为:You shouldn’t talk until you are asked to.故选D。