People can lose their hearing at any age before they are born, as infants, during childhoo

d, or as【C1】______. Each age of onset has a different name and the deafness may have different【C2】______.

Prenatal deafness means that a baby is born deaf. There are several reasons【C3】______ this can happen. If parents are deaf, they may have a deaf baby. There are genes【C4】______ deafness that hearing parents can also【C5】______ on to their child. Other prenatal【C6】______ of deafness can include: accidents; medicine or drugs that the mother takes; illnesses; and genetic syndromes.

Genetic syndromes are a group of characteristics that a child【C7】______ from its parents. There are two very common types of genetic syndromes related to deafness. One is Waardenburg's Syndrome. Its characteristics are very【C8】______. The

person may have pigment (色素)【C9】______: a streak (条纹) of white hair; two different color eyes; or streaks of white in a man's【C10】______. It is【C11】______ to have the physical traits of Waardenburg's Syndrome but not be deaf.

Usher's Syndrome is also fairly【C12】______. Children with Usher's Syndrome are born with a hearing loss and later lose their【C13】______. The first symptoms of this genetic syndrome【C14】______ at【C15】______ A person with Usher's Syndrome will【C16】______ problems seeing well in the dark. Later, they will lose their peripheral (外围的) vision and see only within a tunnel area in front of them. This is called "tunnel vision." Persons may eventually lose more and more of their vision and become blind or【C17】______ blind. If you notice that a(n)【C18】______ person does not see you when you stand at his or her【C19】______, that person may have this syndrome. The best way to communicate with a person who has Usher's Syndrome is to stand directly in front and to sign【C20】______.

【C1】

A． adults

B． friends

C． relatives

D． students