英语语法分析

Only by doing so can we maintain the vigor and vitality of our nation.

只有这样做，我们才能使的国家保持生机和活力。

Many come through periods of stress with more physical and mental vigor than they had before.

许多人在经历了一段时间的压力后，身心都比以前更有活力。

In government laboratories and elsewhere, scientists are seeking a drug able to prolong life and youthful vigor.

在政府实验室和其他地方，科学家们正在寻找一种能够延长寿命、让人保持年轻活力的药物。