THIS EXERCISES ARE DESIGNED TO________ YOUR STOMACH MUSCLES, (STRO...

50. This exercises are designed to________ your stomach muscles, (strong)

READING

(51-60). Choose the word or phrase (a, b, c or d) that best fits the blank space in the

following passage.

In recent years there have, been many (51)____ on air pollution in newspapers and

magazines. Scientists all over the world have warned that our atmosphere is (52)_____

more and more contaminated, and that Man, through his carelessness, may run

(53)_______ of pure air to breathe. Automobiles and industries mainly (54)______ for air

pollution in most cities. They pour into the air such gases as carbon monoxide, sulphur

and nitrogen oxides, which are very (55)______ to humans. Worse still, these gases, after

a series of chemical changes, turn (56)______ toxic acids. They fall down in ‘acid rains’,

raising the acidity in the air, soil and water to dangerous (57)_________ and affecting not

only trees but also fish and other wildlife. Many industrial countries in Europe and North

America have (58)_______ bad effects from those ‘rains’.

(59) ______, Man faces no more urgent problem than that of saving his own survival.

Scientists, social organizations and governments should sit down together to solve the air

(60)______problem.