[填空题]Workers aged 25-34 usually have more employment experience than workers aged 16-24.

[填空题]More media advertising options have more impact on the creative challenge.

[单项选择]National Parks have more and more visitors each year. In the last ten years the number of campers using the camp sites has more than doubled. Camping as a family vacation has suddenly become extremely popular in America. It is a cheap way to travel; its simple pleasures are a pleasant change from hectic urban life; and it can be enjoyed by children of all ages.
In car trunks or in racks on top of cars, families load a tent, sleeping bags, inflatable mattresses, cooking pans and eating utensils, and an ice chest for storing food. When they arrive at a camping ground they find a cleared space in which to pitch their tent, a fireplace for cooking, and usually a picnic table and benches--water and firewood nearby. By evening they are settled under the stars, the campsite around them dotted with lights from cooking fires and lanterns hung from trees.
Vacations are not all in resorts or in the wilderness. Swarms of vacationing Americans visit New York and Washington each year. They
A. Vacations in America.
B. Big Cities in America.
C. American Family Life.
D. Camping as a Family Vacation.