3.I used to spend one hour to study political theory and bussiness management every evening.
4.We shoule insist to forest planting all over the country,which both benefits to present and future generation.

3.I used to spend one hour to study political theory and bussiness management every evening.
4.We shoule insist to forest planting all over the country,which both benefits to present and future generation.

3.I used to spend one hour to study political theory and bussiness management every evening.
4.We shoule insist to forest planting all over the country,which both benefits to present and future generation.

3.I used to spend one hour to study political theory and bussiness management every evening.
4.We shoule insist to forest planting all over the country,which both benefits to present and future generation.

3.I used to spend one hour to study political theory and bussiness management every evening.
4.We shoule insist to forest planting all over the country,which both benefits to present and future generation.

3.I used to spend one hour to study political theory and bussiness management every evening.
4.We should insist  forest planting all over the country,which both benefits to present and future generation.

4.We should insist in forest planting all over the country,which both benefits to present and future generation.

翻译的不错，语法错误也很好，但要注意某些固定搭配以及句型的选择。
1. I also became a victim because my photo which looked like a dead person was placed on the cover of this magazine. 没有问题
2. An American funds organization has come to China to make some investment.
3. I have to spend one hour studying the political theories and the knowledge of enterprise management every evening. 没有问题
4. Nation-wide forestry planting is advantageous to the contemporary as well as the future generations, so that we should preserve it.
5. The key to keeping on developing the rural market economy is to deepen the reform of the price system and the circulating of farm produce.

可以改成：Foresty planting in the nation,which is benefit to both present and future generations,should be done persistently.

企业管理、工商管理：enterprise management ,business administration没有问题。
在职研究生：on-job postgraduates