20、When you exercise too hard, you may feel something．Take note of these feelings because it's time to stop your exercise and get medical attention．

You may breathe a little more heavily than usual during a great exercise, but you should not feel that during a light after- dinner walk．Certain feelings When you exercise lightly could sometimes suggest something serious, says Martha Gulati, MD, at Rush University Medical Center in Chicago．If you're healthy and in good shape but experience any of the warning signs in the form below during an exercise, stop what you're doing and see your doctor at once．

1．The situation that you breathe heavily during a powerful exercise is _______ that you feel during a leisure walk．

A．just like             B．less than            C．not the same as       D．worse than

2．When we are doing sports, we should _______ certain feelings so that we can keep healthy．

A．go on                                    B．pay no attention to

C．not care                                        D．pay more attention to

3．Where is Martha Gulati, MD from?

A．America．          B．Russia．           C．The UK．          D．Australia．

4．If you have low blood sugar, you should _______ during the exercise．

A．have stomachache                          B．have serious headache

C．be unable to keep balance                     D．have chest pain

5．What can we know from the passage?

A．When we feel fainting, it could mean heartburn．

B．When we have serious headache, it could mean stoke．

C．When we have difficulty breathing, it could mean low blood sugar．

D．We can't do exercise after supper．