Have a question about forming passive sentences from active sentences.
1a "The rebels attacked the city from the hilltop."
2a "The teacher yelled at the students from his (teacher's) office."
3a "The spy observed the suspect from his (spy's) car."
For the above active sentences, if I write the following passive sentences:
1b "The city was attacked from the hilltop."
2b "The students were yelled at from the teacher's office."
3b "The suspect was observed from the spy's car."
Are some of the passive sentences not so good?