The policeman warned us________ the busy street when the traffic lights are red.( )
don't cross
not crossing
not to cross
can't cross
---Will you please stay here for the party? ---Sorry, I _____. I have to go to visit my grandfather in hospital.
The notebook ___________ be John's .There is his name on it.
-- I think the red car _______ belong to Miss Wang because she bought a new car yesterday. --It __________be her car’s because her new car is blue.
------Must I finish my homework now ? ------No, you _________ . You can do it tomorrow .
We be too careful while dealing with these social problems.