— Could we practice playing the guitar in the hall, Sir ?                  —No , ___________ you have the principal’s (校长) note.        

You’d better look up the new word in a dictionary _____ you don’t know it ?

Someone called me up in the middle of the night, but they hung up        I could answer the phone.

Put the milk in the fridge,            it will go bad easily. 

You won’t feel happy at school ___ you get on well with your classmates.