Read the passage below carefully and choose the correct answer a, b, c or d. Along with jogging and swimming, cycling is one of the best all-round forms of exercise. It can help to increase your strength and energy, giving you more efficient muscles and stronger heart. But increasing your strength is not the only advantage of cycling. Because you're not carrying the weight of your body on your feet, it's a good form of exercise for people with painful feet or backs. However, with all forms of exercise it's important to start slowly and build up gently. Doing too mlich too quickly can damage muscles that aren't used to working. If you have any doubts about taking up cycling for health reasons, talk to your doctor and ask his/ her advice. Ideally you should be cycling at least two or three times a week. For the exercise to be doing you good, you should get a little out of breath. Don't worry that if you begin to lose your breath, it could be dangerous and there must be something wrong with your heart. This is simply not true; shortness of breath shows that the exercise is having the right effect. However, if you find you are in pain then you should stop and take a rest. 26. This piece of writing is for____. a. children b. doctors c. anyone d. sportsmen and women 27. What is the writer's purpose? a. to amuse b. to worry c. to warn d. to persuade 28. People with back problems might go cycling because____. a. they avoid putting all their weight on their feet b. it can help to strengthen their back c. they can start slowly and build up gently d. it give them more efficient muscles. 29. What is the disadvantage of sudden exercise? a. You can lose your breath. b. You may have a heart attack. c. You can damage muscles that aren't used to working. d. You can be painful. 30. Which of the following is NOT true? a. Cycling is an excellent form of exercise. b. You should do cycling as quick as possible. c. Going cycling regularly and you'll get stronger and healthier. d. If you have any health problem, check with your doctor first làm và giải thích giúp em với ạ . Thanks