The violin will have to be tuned before it _____.

Using a telescope we could see that something     .

Since the project has been ___ on well, you must ___ it on until it is completed.

— What do you want for breakfast, Joe? — I think I _______ some bread and milk.

---When are you going to travel to Beijing? ---The train ______ at six tomorrow morning, and I _______ for the station at four o’clock.