But health ministries, acting alone, cannot re-engineer societies in ways that protect entire populations from the well-known and easily modified risks that lead to these diseases.
然而，卫生部门单凭一己之力无法重塑社会，保护全民免受广为人知并可轻易改变的致病危险带来的侵扰。
2
When calculating the wind loads acting on a railway bridge, an engineer assumes that the wind will act in a horizontal direction. It doesn't always, of course.