Brought about by the constant pressure of lying on a stationary surface, painful ulcers can involve substantial skin loss, sometimes exposing muscle and even bone.
由于躺在静止的平面上持续产生的压力，疼痛性溃疡会伴随大面积皮肤脱落，有时露出肌肉，甚至骨头。
2
Although on the surface the differences between business and consumer marketing may seem obvious, there are more subtle distinctions between the two with substantial ramifications.
尽管表面上企业营销和消费者营销的区别很明显，二者之间存在着更微妙的区别和更重要的分歧。
3
The orbiter was commissioned to search for evidence that water persisted on the surface of Mars for a substantial period of time - long enough to provide a habitat for life.