英语语法分析

This is called a rarefaction and is represented by widely spaced dots.

这个区域称为稀疏区，并用疏散的小点表示。

Objective: For observation and treatment of diabetes followed by rarefaction of bone.

目的：观察和治疗糖尿病伴随骨质疏松。

Objectives: To study the changes in microvascular rarefaction of retinae in hypertensive rats and patients.

目的：了解自发性高血压大鼠和高血压患者视网膜微血管变化。