1. There is no doubt that our educational system leaves something to be desired.
2. An advantage of using the solar energy is that it won t create any pollution.
3. The reason why we have to grow trees is that they can supply fresh air for us.
4. So precious is time that we can t afford to waste it.
5. Rich as our country is, the qualities of our living are by no means satisfactory.
6. The harder you work, the more progress you make.