scab of wheat

例句：

1. 1. The farmer had a scab on his hand that wouldn't heal.
   这位农民的手上有一块不愈合的疮痂。
2. 2. After the injury, he applied a plaster to the scab and waited for it to heal.
   受伤后，他给疮痂贴上了石膏，等待它愈合。
3. 3. The doctor advised him to keep the scab clean and dry to prevent infection.
   医生建议他保持疮痂干净干燥，以防止感染。