短语讲解：
1. The goal is really to put a million of these frontline health workers on the ground in the next four years by the end of the period where we’re measuring progress against the Millennium Development Goals.
by the end of到…为止
例句：He had finished his great works by the end of 1980.
到1980年底, 他已完成了他的巨著。
2. The U.S. is already heavily involved in training health workers through its development agency, USAID, and the National Institutes of Health.
involve in使参与〔陷入, 牵扯到〕
例句：The vast masses there have become involved in the health campaign.
那里的广�
