The Salk vaccine is a major factor in the fight to eradicate polio.

名词解释：人际关系的结构

Comets are still regarded with awe by some people.

The economy of Dallas, Texas, is strong and diversified .

名词解释：冷淡

名词解释：角色

名词解释：维度

适度自我暴露需要掌握的技法有（）

涉外关系的交往技法有（）

Although the Carbon 14 method of dating old objects is not foolproof , it is the best method available at present