Afteraheateddiscussion,theystilldon’tknowatall

來源：國語幫 3.25W

After a heated discussion, they still don’t know at all _______.

A．what is he working out B．what he is working on

C．what did he work on D．what he is working out

考查動詞短語和賓語從句。句意：經過激烈的討論，他們仍然一點也不知道他在做什麼。work on表示“從事於”，work out表示“算出”，分析句子結構可知此處為賓語從句，從句中的working on缺少賓語，故B項正確。