Mary didn’t know who _______ the problem she met with at that time.
—I am going to Sanya for my holiday tomorrow. —_____________.
— Look! The girl ______ long hair is making a snowman. Is she Sandy? — It _______ be her. I’m not sure.
The Maths problem is so difficult that _______ students can work it out.
It’s quite cold outside, you had better _________the windows.
The number of the giant pandas in China is getting but the red crowned cranes are getting .