deafness due to deficiency of blood

例句：

1. 1. He was borndeaf and has never been able tohear properly.
   他出生时失聪，从未能正常听见。
2. 2. The hearing aidshelped her regain some of her hearing.
   助听器帮助她恢复了一些听力。
3. 3. Shewas deaf from birthand had to learn sign languageas a child.
   她从出生时就失聪，必须从小就学习手语。