他花了一整天微调吉他，直到音色完美。

He spent the whole day ___fine-tuning his guitar until the sound was perfect.

吉他手在演出前仔细调音以确保音准。

The guitarist ___fine-tunes his instrument before the performance to ensure perfect pitch.

工程师正在微调空调系统以提高能效。

The engineer ___fine-tunes the air conditioning system for better energy efficiency.

他根据测试结果对算法进行了微调。

He ___fine-tuned the algorithm based on the test results.