5. Estoy feliz
Is that the only one that you need?
Estábamos sirviendo would be the answer for the nosotros form in the imperfect progressive. For future reference, you should check out the Spanish Dict online, it has all of the verbs in every form and tense :)
innovative projector
knitting
purple bicycle
All the noun phrases are basically a person place thing or object with a word describing it :).
Answer:
The correct answer is scientists............!
