The most common types of cancer diagnosed in children ages 0 to 14 years in the United States are leukemias. Although survival rates for most childhood cancers have improved in recent decades, the improvement has been especially dramatic for a few cancers, particularly acute lymphoblastic leukemia, which is the most common childhood cancer. Survival rates remain very low for some cancer types, for some age groups, and for some cancers within a site. Children who have cancer are often treated at a children’s cancer center, which is a hospital or a unit within a hospital that specializes in diagnosing and treating children and adolescents who have cancer. It’s important for childhood cancer survivors to have regular medical follow-up examinations so any health problems that occur can be identified and treated as soon as possible.
3). Many movies have been made by Steven Spielberg.
4). A type of air pollution is caused by hydrocarbons.
5). The kayak was invented by Indigenous people for transportation and fishing.
6). 350 million letters are sent by people every year in Britain.
7). All the cookies had already been eaten by them when I arrived.
8). The factory was opened by us at nine o'clock.
9). The documents are kept in this drawer.
10). We were told by a man to wait outside.
Passive voice is described as the grammatical construction in which the object and the action stated by the verb are emphasized rather than the subject. The subject in such construction becomes the recipient of the action and is acted upon(by the verb). It helps in showing interest in the noun(in object place) which undergoes the action instead of the doer(subject) who performs it.
In order to convert the given sentences from the active voice to the passive voice, the object will be substituted with the subject in order to shift the emphasis. Since the subject is the recipient of the action, it can be omitted or written using 'by' as mentioned above.