题目3单选题
在用相位比较法测量超声波的波长时,选择以下哪种李萨如图形作为参考图形( )A. <img src="https://tihai-oss-cloud.itihey.com/img/c59cc34020337b775f615cd2b1563fd9.jpg">B. <img src="https://tihai-oss-cloud.itihey.com/img/e4f96720f419652963f91d77e7c2c4bc.jpg">C. <img src="https://tihai-oss-cloud.itihey.com/img/461edf1b31acac8671e52cf8e4c85a97.jpg">D. <img src="https://tihai-oss-cloud.itihey.com/img/a57c6f01015f6d8aef44bb9f145f5566.jpg">