词汇讲解：
1. trial n. 测试, 试验, 考验
例句：They are doing clinical trials on a new drug.
他们正在做一种新药物的临床试验。
2. drill n. 操练, 训练
例句：The recruits drilled regularly.
新兵们定时操练。
3. ambulance n. 救护车
例句：He was sent to hospital by ambulance.
救护车将他送往医院。
4. surgery n. 外科诊所; 外科手术
例句：Your condition is serious and requires surgery.
你的情况很严重, 需要动外科手术。
5. provide vt. 提供
例句：On Sundays his landlady provided dinner as well as breakfast. <
