be at drill meaning in Chinese

正在出操

• drill:    n. 【动物；动物学】(西非的)鬼狒 ...
• drill:    n. 1.【军事】操练，演习；(严格 ...
• drill in:    套管钻进; 钻开油气层

Examples

1. The soldiers were at drill in the barrack yard .
   士兵们在军营里操练。
2. The soldiers were at drill in the barrack-yard .
   士兵们在兵营练兵场操练。
3. The students were at drill on the playground
   同学们正在操场上操练。
4. The soldiers were at drill
   士兵们正在操练。