【题目】The great pianist performed in the centre of stage, _______ command the keys were producing wonderful tunes.
A. at whomB. at whose
C. in whomD. in whose
在线课程【答案】B
【解析】
考查非限定性定语从句。句意：这位伟大的钢琴家在舞台中央演奏，在他的指挥下，琴键走出美妙的乐曲。at sb's command 是固定搭配，表示“在某人的指挥之下”，用whose在从句中作定语，故B项正确。