Answer:
1. b)is playing
2. a)are,doing
3. a)are eatting
Explanation:
The continuous present is a term that refers to a verbal form where the verb appears in the present tense, but indicates a continuous and progressive activity, being used in both the indicative and the subjunctive form, always indicating an activity that is in progress. This verbal mode is easily identifiable with the suffix "ing" at the end of verbs.
All the mustard phrases in the question above were supplemented with the verb in the present continuous that best fit the blanks and provided a grammatically correct written phrase.