Which adjective describes something that is unlikely to happen?
答案解析
**Core Concept:** Adjective meaning (unlikely).
**Analysis:** **C. unlikely** directly means 'not probable'.
- **A. utmost** means 'greatest extent'.
- **B. vain** relates to futility or pride.
- **D. useful** means 'practical'. Only **C** aligns with probability.
正确答案：C