【单选题】第八周线上课堂测试:阅读理解Porous carbon microspheres (PCMSs) were prepared by ultrasonic spray pyrolysis and attached with microwires composed of carbon fibre paper after the dip and dry method (Fig. 2a,b and Sup...
【单选题】Radar (雷达) 1. Children enjoy shouting at a high wall and hearing the sound come back to them. These sounds are called echoes (回声). Echoes have given us a number of 'valuable tools. 2. Echo sounding de...