Questão 17

    Flying is the safest way to travel...or is it? Some doctors
think the airplane is a dangerous place, especially for the old
or the unhealthy.
    Although the airplane is pressurized, there is less oxygen
[5] than on the ground. So anyone who has had a heart attack
should not try for at least two weeks after the attack. After an
operation, you should stay on the ground for at least ten days.
    Sitting on a plane for many hours – especially $\in$ economy
class where there isn’t very much leg room – gives everyone
[10] aches and pain, so you should get some exercise, especially
on long flights.
    Flying also causes dehydration. If you drink or eat too
much, you’ll wake up feeling sick. Everyone needs to drink
more $\in$ the air, but you shouldn’t drink alcohol because it
[15] makes you even more thirsty.
    The most common problem is jet lag. You should change
to your new time zone as soon as possible, and you shouldn’t
sleep if it’s still daylight.
    Crowded airports, long lines, and delays cause stress and
[20] high blood pressure. So, be careful! Flying is the safest way to
travel, but is it the healthiest?

(Move Up, Heinemann )

From the text it’s also possible to get