1. This land is rich with petroleum.
    这片土地蕴藏着丰富的石油。

2. Petroleum is a valuable resource.
    石油是一种珍贵的资源。

3. Likewise, a limited amount of petroleum can be found under the Earth's surface.
    同理，地表之下只能找到储量有限的石油。

4. In this category, we may also include large payments made to ruling families or their close advisers in order to secure arms sales or major petroleum or construction contracts.
    这一大类也包括为得到武器销售或重大的石油、建筑等项目合同而向权势家族及其身边顾问所付出的大笔款项。