ПОЖАЛУЙСТА ПОМОГИТЕ  раскройте скобки и поставьте глагол в нужную форму. и объясните почему так раскрыли скобки ,пожалуйста
1.  Dental  students ____ ( to receive ) their education in specialized dental  schools. 
2.  In Russia a training course for certified dental  students ____ ( to last ) five academic years.
3. Apart from general medical disciplines, the four principal divisions of dentistry ____ ( to recognize ) in curricula in Russia.
4.  Entry to a dentistry department ____ ( to depend) on the resul ts of com-petitive examinations.
5.  For hundreds of years people ____ ( to believe ) that tooth decay ____ ( to cause) by a worm in the teeth.
6. Short courses ___ (to offer) regularly to dentists to keep them informed of the new developments in dentistry.
7 .  Dentistry ____ ( to consider ) well-paid and secure employment in Great  Britain.
8.  Study of basic medical  and dental  subjects ____ ( to interconnect ) closely with clinical dentistry.
9.  Anatomy , biochemistry and physiology ____ ( to study) at medical  uni-versities.
10.  Before starting to work wi th patients in clinics, students ____ ( to teach) the techniques on phantom heads.
11.  Doctors ____ ( to look) for new ways to help patients.
12.  Medical  science ____ ( to make ) a lot of progress in recent years both in treatment and diagnosis.
13.  Many simple measures ____ ( to take ) to prevent dental  diseases.
1 4.  Preventive care ____ ( to aim) at the two major tooth troubles:  caries and gum diseases.
15.  Preventive orthodontics ____ ( to be ) another aspect of early treatment.

1.  Dental  students receive (Present Simple - мн.число) their education in specialized dental  schools. 2.  In Russia a training course for certified dental  students lasts (Present Simple - ед.число) five academic years.3. Apart from general medical disciplines, the four principal divisions of dentistry are recognized (страдательный залог в Present Simple) in curricula in Russia.4.  Entry to a dentistry department depends (Present Simple - ед.число) on the resul ts of com-petitive examinations.5.  For hundreds of years people  believe (Present Simple -мн.число) that tooth decay is caused (страдательный залог в Present Simple) by a worm in the teeth.6. Short courses are offered (страдательный залог в Present Simple) regularly to dentists to keep them informed of the new developments in dentistry.7 .  Dentistry is considered (страдательный залог в Present Simple) well-paid and secure employment in Great  Britain.8.  Study of basic medical  and dental  subjects  is closely interconnected _(страдательный залог в Present Simple) with clinical dentistry.9.  Anatomy , biochemistry and physiology are studied_(страдательный залог в Present Simple) at medical  uni-versities.10.  Before starting to work wi th patients in clinics, students are taught_(страдательный залог в Present Simple) the techniques on phantom heads.11.  Doctors  look (Present Simple - мн.число) for new ways to help patients.12.  Medical  science makes (Present Simple - ед.число) a lot of progress in recent years both in treatment and diagnosis.13.  Many simple measures are taken (страдательный залог в Present Simple) to prevent dental  diseases.1 4.  Preventive care aims (Present Simple - ед.число) at the two major tooth troubles:  caries and gum diseases.15.  Preventive orthodontics is (Present Simple - ед.число) another aspect of early treatment.