Today it's much easier to be healthy than it is（was) in the past.Modern people know more about healthy(health),have better food,and live in clean(claener) surroundings.Also,scientists and doctors had(have) learnt how to deal with many diseases.Most people can quickly get help from a doctor since(if) they are ill.As a result,people in the modern world genereally(generally) live much more(去掉） longer than people in the past.People in rich country（countries） expect to live twice so(as) long as people who lived a few hundred years age(ago).Therefore(However),there are still some countries (加where)people have shorter lives and have not enough(加food) to eat.
括号里是改正前面一个词的错误,加.是指加上一个词