Answer:mouthful, teaspoonful
Explanation:
The answer is more than likely A. present progressive form.
1. A predicative nominative is a noun or a pronoun which follows a linking verb and refers to something before that verb. In your case, the correct answer is B, because "a shelter" goes after the linking verb "is", and refers to "a lean-to".
2. A participle has the form of infinitive + ing. In this case, the answer is D, flourishing.
It was the 1930s when the period of To Kill a Mockingbird set.