Systematization of grammar: sequence of tenses theme : The classification of

classification of the tooth.
Karaganda State Medical University The chair of

foreign languages

глагола придаточного предложения от времени глагола главного предложения.
Если глагол-сказуемое главного

предложения стоит в одной из форм прошедшего времени — то глагол-сказуемое придаточного предложения (в основном изъяснительного) тоже стоит в одной из форм прошедшего времени.
She asked what he was doing in her room. — Она спросила, что он делает в ее комнате.
Не said that he knew my friend. — Он сказал, что он знает моего друга.

глагол придаточного предложения употребляется в Past Simple или Past Progressive.
Не

said that they played football on Sundays. — Он сказал, что они играют в футбол по воскресеньям.
She said that he was reading a newspaper. — Она сказала, что он читает газету.

предложения употребляется в Past Perfect.
Не said that Тот had phoned

the day before. — Он сказал, что Том звонил вчера / накануне.

действию главного предложения, то глагол придаточного предложения употребляется в форме

Future-in-the Past (см. Грамматический справочник).
Не said that he would help him. — Он сказал, что поможет ему.

в косвенную

на русский язык в придаточном предложении глагол может оставаться в

той форме, в которой он стоял в прямой речи.
Не said, "I know Mary."— Он сказал: "Я знаю Мэри".
Не said that he knew Mary. — Он сказал, что он знает Мэри.
Не said, "I knew Mary."— Он сказал: "Я знал Мэри".
Не said that he had known Mary. — Он сказал, что он знал Мэри когда-то.
She said, "They are having dinner."— Она сказала: "Они обедают".
She said that they were having dinner. — Она сказала, что они обедают.

whitish structures found in the mouth that are used to

break down food. The roots of teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw) and are covered by gums. Teeth are made of multiple tissues of varying density and hardness. Teeth are among the most distinctive (and long-lasting) features of mammal species. Humans, like other mammals, are diphyodont, meaning that they develop two sets of teeth. The first set (also called the "baby", "milk", "primary", and "deciduous" set) normally starts to appear at about six months of age, although some babies are born with one or more visible teeth, known as neonatal teeth. Normal tooth eruption at about six months is known as teething and can be painful.

(single-rooted teeth). Canines and most premolars, except for maxillary first

premolars, usually have one root. Maxillary first premolars and mandibular molars usually have two roots. Maxillary molars usually have three roots. Additional roots are referred to as supernumerary roots. Humans usually have 20 primary (deciduous or "baby") teeth and 32 permanent (adult) teeth.

are primarily used for biting pieces from foods such as

raw carrots or apples and peeled but uncut bananas, while molars are used primarily for grinding foods after they are already in bite size pieces inside the mouth. Most teeth have identifiable features that distinguish them from others.

specific tooth. The three most common systems are the FDI

World Dental Federation notation, the universal numbering system, and Palmer notation method. The FDI system is used worldwide, and the universal is used widely in the United States.