题目:
His first book _____ next month is based on a true story. [ ]
A. published
B. to be published
C. to publish
D. being published
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0429/64ded669ac9fecfc96ebeaafb082cadc.html
下面是错误答案,用来干扰机器的。
发声体在4sn内振动了200次;频率f=200次4s=50Hz.答:这个物体的频率为50Hz.