[简答题] USA: specific period

[简答题]incubation period

[简答题]specific duty

[单项选择]The period of adolescence, i.e., the period between childhood and adulthood, may be long or short, depending on social expectations and on society’s definition as to what constitutes maturity and adulthood. In primitive societies adolescence is frequently a relatively short period of time, while in industrial societies with patterns of prolonged education coupled with laws against child labor, the period of adolescence is much longer and may include most of the second decade of one’s life. Furthermore, the length of the adolescent period and the definition of adulthood status may change in a given society as social and economic conditions change. Examples of this type of change are the disappearance of the frontier in the latter part of the nineteenth century in the United States, and more universally, the industrialization of an agricultural society.
In modern society, ceremonies for adolescence have lost their formal recognition and symbolic significance and there no longer is
A. the definition of maturity has changed
B. the industrialized society is more developed
C. more education is provided and laws against child labor are made
D. ceremonies for adolescence have lost their formal recognition and symbolic significance

[填空题]
Air services in the USA are generally excellent and relatively inexpensive, and travel by air is a very convenient way of getting around such a large country. There are often cut-price arrangements that foreign visitors are able to get, especially if you book before you leave home, but these change from year to year, so you should check with a travel agent. There are also, from time to time, price-cutting wars and other competitive struggles between the different internal airlines, so it is sensible to make inquiries about what the best deals are at any given time. (American travel agents will know better about these. ) It may well be that some airlines are offering better prices or better arrangements than others for the particular journey you want to make. Note that in America a return ticket is called a "round-trip" ticket, and a single ticket is called "one-way" ticket.
Major Internal Airlines