[填空题]Plant species are dispersed over a large area with the help of______.

[填空题]Plant species are dispersed over a large area with the help of ______.

[填空题]The short-lived, rapidly dispersed species are often called ______.

[单项选择]A supermarket is a large-area, low-cost, high-volume, self-service operation designed to serve the consumers’’ various needs for food, clothes and other useful products in our daily life. A supermarket store can be independently owned, although most supermarket stores are operated by supermarket chains. Supermarkets have moved in several directions to further build their sales volume. They have opened much larger stores, with today’’s selling space occupying about 18,000 square feet as compared to 11,700 square feet in the 1950s. Most of the supermarket chains now operate fewer but larger stores. Supermarkets deal in a great number and variety of items. A typical supermarket handled 3,000 items in 1946 and now handles around 8,000. Nowadays, supermarkets have been hit hard by a number of competitors meeting better defined customer needs with respect to the variety of products and price levels. So they are trying to improve their marketing positions. The most important increas
A. fewer but larger stores
B. more but smaller stores
C. more and larger stores
D. fewer and smaller stores

[填空题]Although they plant trees in this area every year, ______________________(山顶仍然是光秃秃的).

[单项选择]

Driving a large truck over mountain roads is not the usual way that a schoolteacher begins her day—especially if she is a preschool teacher. But Mrs. Beth Miller does this five days every week. Her unusual schoolhouse-on-wheels is really a large truck. The back of the truck has been made into a classroom in order to carry the advantages of modem education to remote area of the state of West Virginia. In many rural areas of this state it is impossible for small children to go to regular schools because of the isolation caused by the many hills and valleys of Appalachia.
The purpose of the schoolhouse-on-wheels project is to develop basic skills and social behavior in children three to five years of age. This is accomplished through games, exercises, toys and simple handicrafts. The schoolhouse-on-wheels also teaches the young children to recognize 300 to 400 words on the printed page. This is a great advantage in helping the pupils to learn to read when they begin re
A. The teachers.
B. The children’s parents.
C. The federal government.
D. A certain company.