1. The writing on the old document was indiscernible due to its age.
由于年代久远，这份古老文件上的文字已经看不清了。
2. The faint whispers were indiscernible to the human ear.
微弱的耳语对人耳来说难以察觉。
3. The reasons behind his decision were indiscernible to me.
他做出这个决定的原因对我来说难以理解。