Замените инфинитивы, данные в скобках, герундием. с объяснением, , и полным написанием предложения. 1. after the recovery the patient stopped (to lose) his weight. 2. my brother had to give up ( to smoke) due to chronic bronchitis. 3. the young physician tried (to introduce) various new ways of treatment. 4. you must avoid ( to catch) a cold as you have just beem ill with pneumonia. 5. what has prevented you from ( to attend) this lecture?

1. After the recovery the patient stopped losing his weight.
2. My brother had to give up smoking due to chronic bronchitis. 
3. The yound physician tried introducing various new ways of treatment. 
4. You must avoid catching a cold as you have just been ill with pneumonia. 
5. What has prevented you from attending this lecture?

Не совсем понял, какое требуется объяснение. Во всех случаях инфинитив заменяется формой глагола с -ing.