選擇柔和的速度慢的旋律感較強的作品，例如：肖邦的夜曲等等，目的是檢測鋼琴對音色細微的表現情況，檢測「暗度和薄度」；

Yes, different piano can have different tone colours and sounds, even if we play the same pieces of Chopin on different pianos. Good pianos can have more sensitivity and richer tone colours than poor pianos. It is because good pianos can show much more different varieties of sounds like loud, soft,medium tones etc. So, different 「暗度和薄度」of tones can be revealed in different pianos, especially if you play the pieces of Chopin, in which frequent change in loudness and softness of sounds are required.
所以,選擇柔和的速度,慢的旋律感較強的作品，例如：肖邦的夜曲等等，是可以檢測鋼琴對音色細微的表現情況，檢測音色之「暗度和薄度」。

i have no idea what you are talking about. cant help you. sorry.