You must be quiet in the library. If you make a lot of , you may disturb others.
The workers in the Huashan Mountains have to ______rubbish to keep the mountains clean.
— Whose shoes are these?— They ____ be Mike’s. They are much too large for him.
The little child was too _______ to hear the end of the long speech.
We should learn_______ each other.
Attention , please! All the mobile phones _________during the meeting.