不定项选择题 When we analyze the salt salinity (盐浓度) of ocean waters, we find that it varies only slightly from place to place． Nevertheless, some of these small changes are important． There are three basic processes that cause a change in oceanic salinity． One of these is the subtraction of water from the ocean by means of evaporation． In this manner, the salinity is increased, since the salt stays behind． If this is carried to the extreme, of course, white salt would be left behind ; this, by the way,is how much of the table salt we use is actually obtained． The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean． Here the ocean is being diluted so that the salinity is decreased． This may occur in areas of high rainfall or in coastal regions where rivers flow into the ocean． Thus salinity may be increased by the subtraction of water by evaporation, or decreased by the addition of fresh water by precipitation． Normally, in hot regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation． similarly, in coastal． Grandma, who used to live upstairs, is now the voice on long distance, and the working parent is far too beaten down each day to spend evening relaxation time listening to the sandbox experience of an eager four-year-old． So family conversation is as extinct as my old toys and parental questions such as "What have you been doing, Bobby? " have been replaced by "I 'm busy, go watch television． And watch TV they do; count them by the millions． But it's usually not children's television that children watch． Saturday morning, the children's hour, amounts to only about 8 percent of their weekly viewing． Where are they to be found?Watching adult television, of course, from the Match Game in the morning, to the afternoon at General Hospital, from the muggings and battles on the evening news right through the family hour and past into Starsky and Hutch． That's where you find our kids, over five million of them, at 10 p．m．, not fewer than a million until after midnight! All of this is done with parental permission． Television, used well, can provide enriching experiences for our young people, but we must use it with some sense． When the carpet is clean, we turn off the vacuum cleaner． When the dishes are clean, the dishwasher turns itself off． Not so the television, which is on from the sun in the morning to the moon at night and beyond! Parents must exercise some control and show some concern about the cultural influence on the child when a program not intended for that child is viewed． Parents need to intervene． Nonintervention may be a wise policy in international affairs, but the results of parental nonintervention will not be wise at alL． The working parent is not willing to listen to her (his) four-year-old child talking about his sandbox games because she (he) is _____