Ilate tomorrow.we are very busy at the officehave to, must) the drivers before they crashed into each other.(could, were able to) in without a ticket. not a chance. ( may not, cannot) to type this letter.it is very important. (needn't, mustn't) i think to relax more. (should, could) you wear a hat when you go out in strong sunlight.(have to, must) david as a taxi driver. he can't drive. ( might not, couldn't)

1) must 2) could 3)  cannot 4)needn t 5)should 6) have to 7) couldn t

laughter is strong medicine. It draws people together in ways that trigger healthy physical and emotional changes in the body. Laughter strengthens your immune system, boosts mood, diminishes pain, and protects you from the damaging effects of stress. Nothing works faster or more dependably to bring your mind and body back into balance than a good laugh.Laughter triggers the release of endorphins, the body’s natural feel-good chemicals. Endorphins promote an overall sense of well-being and can even temporarily relieve pain.Laughter protects the heart. Laughter improves the function of blood vessels and increases blood flow, which can help protect you against a heart attack and other cardiovascular problems.

16 Listen! She is practicing the piano.
17.My friend is playing the guitar every evening.
18.Maria wants to improve her English.
19.She does a language course in London at the moment.
20.She is living far from London and she must take the tube to get her language school.
21.It is only five minute walk to the nearest tube station.
22.The tube will live at half past eight.
23.The first lesson will begin at 9 o'clock.
24.In the afternoons ,the school will offer sightseeing tours in and around London.
25.Today the students of the language school will go to Windsor.