Помогите выбрать правильный вариант
1. I can`t talk on the phone right now because I have stop ________ every few minutes.
a) to cough
b) coughing
c) to have coughed
d) to coughing
2. You must try ________ warm and drink plenty of liquids.
a) keeping
b) to keep
c) to have kept
d) having kept