Backward Extension

With Improving market economic system and the gradual extension of the reform and opening up, discovering economical and cultural backward country how to realize the development of social economic sound and fast is contemporary issues.

伴随着市场经济体制的日臻完善和改革开放的逐步深化，探索经济文化落后国家如何实现经济社会又好又快发展，是我们党面临的重大时代课题。

Jam is a backward-compatible extension of the Java platform, v1.0 ( with two new keywords: mixin and inherited).

Jam是一种向后兼容的Java平台V1.0扩展（带有两个新关键字：mixin和inherited）。

The authors conclude that spondylolysis is mainly the fatigue fracture due to locally increased stress and is contributing most by backward extension of lumbar spine.

作者认为，椎弓峡部裂实质上主要是由局部应力增高而引起的疲劳骨折，而腰椎后伸与其关系最为密切。