铅影响血红素合成的主要作用是（）。 A.抑制血红素合成 B.刺激含巯基的酸 C.激活

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Section C
Directions: Read the following text and choose the most suitable heading from A-F for each paragraph. There is one extra heading which you do not need.

A．Repeating a goal makes it stick.

B．Pleasing other people doesn't work.

C．Roadblocks don't mean failure.

D．Specific, realistic goals work best.

E. Positive self-talk boosts your attitude and motivation.
F. It takes time for a change to become an established habit.
 
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When it comes to making a change, the people who succeed are those who set realistic, specific goals. Let’s say you want to run a marathon. If you try to run the entire distance of 26.2 miles tomorrow without any training, you're unlikely to succeed. It takes the average person 4 months of training to run that far! Part of staying motivated is being specific about what you want to achieve. “I'm going to recycle all my plastic bottles, soda cans, and magazines” is a much more achievable goal than “I'm going to do more for the environment.” And that makes it easier to stick with.
 
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It will probably take a couple of months before any changes — like getting up half an hour early to exercise — become a routine part of your life. That's because your brain needs time to get used to the idea that this new thing you're doing is part of your regular routine.
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Write your goal down every day to keep you focused and remind you how much you want it. Research shows that writing down a goal is part of the mental process of committing to it. Meanwhile, say your goal out loud each morning to remind yourself of what you want and what you're working for. Every time you remind yourself of your goal, you're training your brain to make it happen.
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The people who love you can help you stick with a goal or make a change. But the key to making any change is to find the desire within yourself — you have to do it because you want it, not because a girlfriend, boyfriend, coach, parent, or someone else wants you to. It will be harder to stay on track and motivated if you're doing something out of obligation to another person.
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If you slip up, don’t give up. Forgive yourself and make a plan for getting back on track. Slip-ups are actually part of the learning process as you retrain your brain into a new way of thinking. It is normal to mess up a few times when trying to make a change. Instead of feeling discouraged, view slip-ups as lessons and reminders of why you’re trying to make a change. When you mess up, it’s not a fault — it’s an opportunity to learn something new about yourself. Say your goal is to fight less with your brother or sister. You may learn that it's better to say, “I can’t talk about this right now” and take time to calm down when you feel your temper growing out of control.