The main / important point / conclusion / reason….
The point to note here…
There are three major reasons…
3. but 和 however表示对比，常常用来提示重要信息，例如：
The rising birth rate is not due to increased fertility, but to a sharp decline in the death rate.
Why is a piped water supply so important? Disease due to contaminated water is a common cause of death in childhood.
Death control can be achieved autonomously. In other words, the death rate can be cut without anything else changing.
In conclusion/we can conclude
One of the primary conclusions
Such as these include
To illustrate among these are
The developing countries are dependent on cash crops – sugar, coffee, cacao, cotton.
Precipitating/violent/unexpected factors are those which reduce the food supply (droughts, floods, wars, epidemics)…
The main reason for (提示：下文信息重要) the reduction in the death rate in the developing world has been improved public health measures. For example, (提示：下文信息不重要，仅仅是为了用来证明前面的观点) in Sri Lanka the death rate was halved over ten years by spraying the mosquitoes which carry malaria.
Why (提示：问题的答案中有读者应该关注的重点) is it so easy to cut the death rate in this way and yet so hard to reduce the birth rate? One answer (提示：这只是众多答案中的一种，并不是最重要的。) is that public health measures can be very cheap. Anti-malarial spraying is inexpensive. But this is not the important point (提示：but后面的是非常重要的信息). For birth control programmes to be successful, a change in attitude is required, whereas death control can be achieved autonomously. In other words, (提示：这里是作者想要强调的重要信息) the death rate can be cut without anything else changing.
Provide a Better Life for Senior Citizens Now we have a growing population of senior citizens. To ensure happy lives for them has become a focus of attention. Our traditiona
Passage Twenty-five (Exploration of the Titanic) After resting on the ocean floor, split asunder and rusting, for nearly three-quarters of a century, a great ship seemed to