用法:
1 (medical 医) early form of trephine （早期的）环钻, 环锯.

用法:
2 (engineering 工) bore for drilling a mine shaft 钻井机.

• recession
• reckon
• recognition
• recognize
• recollect
• recommend
• recommendation
• record
• recover
• recovery
• recreation
• recruit
• reduce
• reduction
• refer
• reference
• refine
• reflect
• reflection
• reform
• refresh
• refreshment
• refrigerator
• refugee
• refusal