Choose one sentence that has the same meaning as the root one:
People think Mrs. Nga is a good step mother.
It is thought that Mrs. Nga is a good step mother.
It is believed that Mrs. Nga to be a good step mother.
Mrs. Nga is a good step mother to be thought.
Mrs. Nga is thought she is a good step mother.
It is thought that Mrs. Nga is a good step mother.