又一道关于不定式的英语题I had no idea of the machine ( ) already.A to test B _英语解答

又一道关于不定式的英语题
I had no idea of the machine ( ) already.
A to test B having been tested C testing D having tested
为什么选B?

人气：416 ℃　时间：2020-05-28 15:13:43

解答

句子意思是:我不知道机器已经测试过了
因为有already,可以肯定用完成时
因为machine 是被测试的,所以用被动
结合起来就是 having been tested