8zd. EL PLURAL DEL SUSTANTIVO. THE PLURAL OF NOUNS (Tema III, desde la página 27 hasta la pagina 33 de Gramática Inglesa para Estudiantes Españoles)

8zd) Choose the correct form of the verb, singular or plural (Capítulo III, desde la página 27 a la página 33 de Gramática Inglesa para Estudiantes Españoles):

8zd) Choose the correct form of the verb, singular or plural (Capítulo III, desde la página 27 a la página 33 de Gramática Inglesa para Estudiantes Españoles):
1. The crowd (was/were) held back by security guards
2. The herd (solves/solve) this problem by forming a defensive circle when marauding wolves attack
3. The herd (is/are) swimming around in the blood-red sea as this killing continues
4. The aircraft (was/were) about 20 miles apart
5. Politics (is/are) a relationship business
6. The crossroads (was/were) in a narrow gully
7. Carson's headquarters (is/are) in a vast metal building on the road into Rincon