There must be many people _______ for the train at the train station because of the snow.
I ___ an article about first aid. It’s useful in emergency situation.
It is helpful to _____ a good habit of reading in language learning.
Oh, it ___so nice. What beautiful music it is!
—Someone is knocking at the door. Is it Ann? —It ________ be her. She is giving a performance at the theater now.
—Must we clean the room at once? —No,you ________.You can do it after school.