He is a very careful man, but he ________ make mistakes which seem ridiculous

----When can I come for the photos? I need them tomorrow afternoon. ----They      be ready by 12 o’clock.

All the doctors in the hospital insisted that he ____ badly wounded and that he ____ at once.

 Look at the clock! It's time ______ work.

According to the air traffic rules, you ___ switch off your mobile phone before boarding.