We must keep the noise under 50dB(分贝) here.The noise must ______ ______under50dB here
问题描述:
We must keep the noise under 50dB(分贝) here.The noise must ______ ______under50dB here
答
be kept
be controlled
变为被动语态吗?是的那就是了be keptbe controlled 都可以