Open the brackets and put the verb in the Present Perfect Continuous tense. Write the full form of the verb. Sherry (cook) a cake for the party since morning.

1. Identify the subject: Sherry (singular).
2. Identify the tense: Present Perfect Continuous.
3. Form the tense: has/have + been + verb-ing.
4. Apply to the verb 'cook': has been cooking.