单选题 The noise was so faint that you had to ______ your ears to hear it.
【正确答案】 C
【答案解析】[解析] 句意：声音如此微弱，你必须把耳朵竖起来才听得见。strain使紧张；尽力使用。stir使微动；移动。strengthen加强；巩固。stride跨越。