The plan was that the two parties should first reach an agreement on the basic the detail

问题补充：

The plan was that the two parties should first reach an agreement on the basic ,the details to be worked but later.

A. standards

B. practice

C. habits

D. principle

答案：

A. standards

B. practice

C. habits

(答案→)D. principle

解析：on the basic principle 基本原则上。