读“非洲气候类型”图，完成下列问题：

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    Humans are much worse at estimating risk than we think we are. While we overestimate the risk of rare but disastrous occurrences, such as being attacked by a shark, many of us seriously underestimate the risk of behaviors that reduce our lifespan (寿命), such as smoking.

    In fact, there are two types of risks — acute and chronic. Acute risks are those that may kill you immediately, such as a car accident.

    Chronic risks don't kill you immediately but rob you of your life a little at a time. If you choose to eat an unhealthy diet, for instance, you may appear to be getting away with this, but you risk developing illnesses in future that may shorten your life.

    The problem is we value things much less when they occur in the future. Distant events are abstract — we don't know how and when they might affect us -~ so we care less about them.

    Take smoking for example. It is just about the worst choice you can make for your health. Every two cigarettes that you smoke takes 30 minutes off your lifespan.

    In contrast, eating vegetables is clearly very good for you, with each serve increasing your lifespan by two hours. This is a massive health gain and clearly should be a strong motivator for you to eat healthily.

    Drinking coffee is also good for you, though with limited health gains. Each cup of coffee (assuming you drink reasonably), is associated with approximately a ten-minute gain in your lifespan.

    Even drinking alcohol may add to your lifespan, with each serve adding 30 minutes to the length of your life. But this health gain is only true for the first drink; following drinks shorten lifespan. Alcohol also causes an acute risk when consumed in excess. Too much drinking gives you a 25 in one million chance of sudden death.

    We shouldn't be too nervous about exposure to risks. Life is all about making decisions about risks and rewards, and we all have a different starting point for what we consider acceptable risks to take. Even if we don't always make the healthiest decisions, at least we can make ones that are fully informed.