The term childhood diseases denotes those diseases that characte stically occur during an age span that begins with the fetus and extends through adolescence．This is a period typified by change，both in the child himself and in his immediate environment．Changes in the child related to growth and development are so striking that it is almost as if the child were a series of distinct yet related individuals as he passes through infancy，childhood，and adolescence．Changes in the environment occur as the surroundings and contacts of a totally dependent infant become those of a progressively more independent child and adolescent．⑦Health and disease during the period from conception to adolescence must be understood against this backdrop of changes．
Although，for the most part，the diseases of childhood are similar to those of the adult，there are several important differences．For example，certain specific disorders，such as precocious puberty，are unique to children；others，such as acute nephritis--inflammation of the kidney--are common in children and infrequent in adults．At the same time，some diseases that are common in adults are infrequent in children．These include essential hypertension(high blood pressure of unknown cause)and gout． Finally,a major segment of pediatric care concerns the treatment and prevention of congenital anomalies，both functional and structural．
Apart from variations in disease due to differences between children and adults，certain other features of diseases in children need to be emphasized．Infectious disorders are prevalent and remain 8 leading cause of death，although individual illnesses are often mild and of minor consequence．Most instances of the common communicable diseases，such as measles，chicken pox，and mumps，are encountered in childhood．Disorders of nutrition，still of great concern，especially but not exclusively in developing countries，are of extreme importance to the growing and developing child．The unique nutritional requirements of children make them unusually susceptible to deficiency states：vitamin-D deficiency causes rickets，a common disorder of children in developing countries，and only rarely causes any disease in adults．The major environmental hazards that endanger the health of young children are either unavoidable，as in air pollution，or accidental，as in poisoning and in traffic injuries．0lder children，especially adolescents，are exposed，as are adults，to environmental hazards that they deliberately seek，such as cigarette smoking and the use of alcohol and other drugs．[390 words]
1．Childhood diseases are______．
A．generally caused by the change of the child himself
B．caused primarily by the change of the child’S immediate environment
C．usually associated with the changes that a child has to undergo in his growth and development
D．characterized by a series of distinct yet related stages
2．The disease that an adult unusually suffers from is______．
A．a(chǎn)cute nephritis
B．hypertension
C．mental disorders
D．precocious puberty
3．According to this passage，______.
A．childhood diseases are often mild and of minor consequence
B．childhood diseases never lead to death
C．children are rarely exposed to major environmental hazards
D．some children even intentionally pursue particular environmental hazards
4．It iS TRUE that______．
A．the diseases infrequent in adults may not be So in children
B．childhood diseases are often mild and of minor consequence
C．children are less susceptible to infections than adults
D．children are more susceptible to infections than adults
5．The last paragraph is mainly about______．
A．variations in childhood diseases
B．some remarkable characteristics of childhood diseases
C．prevalent infectious disorders in children
D．several important differences between childhood diseases and adult diseases
Although，for the most part，the diseases of childhood are similar to those of the adult，there are several important differences．For example，certain specific disorders，such as precocious puberty，are unique to children；others，such as acute nephritis--inflammation of the kidney--are common in children and infrequent in adults．At the same time，some diseases that are common in adults are infrequent in children．These include essential hypertension(high blood pressure of unknown cause)and gout． Finally,a major segment of pediatric care concerns the treatment and prevention of congenital anomalies，both functional and structural．
Apart from variations in disease due to differences between children and adults，certain other features of diseases in children need to be emphasized．Infectious disorders are prevalent and remain 8 leading cause of death，although individual illnesses are often mild and of minor consequence．Most instances of the common communicable diseases，such as measles，chicken pox，and mumps，are encountered in childhood．Disorders of nutrition，still of great concern，especially but not exclusively in developing countries，are of extreme importance to the growing and developing child．The unique nutritional requirements of children make them unusually susceptible to deficiency states：vitamin-D deficiency causes rickets，a common disorder of children in developing countries，and only rarely causes any disease in adults．The major environmental hazards that endanger the health of young children are either unavoidable，as in air pollution，or accidental，as in poisoning and in traffic injuries．0lder children，especially adolescents，are exposed，as are adults，to environmental hazards that they deliberately seek，such as cigarette smoking and the use of alcohol and other drugs．[390 words]
1．Childhood diseases are______．
A．generally caused by the change of the child himself
B．caused primarily by the change of the child’S immediate environment
C．usually associated with the changes that a child has to undergo in his growth and development
D．characterized by a series of distinct yet related stages
2．The disease that an adult unusually suffers from is______．
A．a(chǎn)cute nephritis
B．hypertension
C．mental disorders
D．precocious puberty
3．According to this passage，______.
A．childhood diseases are often mild and of minor consequence
B．childhood diseases never lead to death
C．children are rarely exposed to major environmental hazards
D．some children even intentionally pursue particular environmental hazards
4．It iS TRUE that______．
A．the diseases infrequent in adults may not be So in children
B．childhood diseases are often mild and of minor consequence
C．children are less susceptible to infections than adults
D．children are more susceptible to infections than adults
5．The last paragraph is mainly about______．
A．variations in childhood diseases
B．some remarkable characteristics of childhood diseases
C．prevalent infectious disorders in children
D．several important differences between childhood diseases and adult diseases