PARAGRAPH 3

　　The ephemeral plants evade drought. Given a year of favorable precipitation, such plants will develop vigorously and produce large numbers of flowers and fruit. This replenishes the seed content of the desert soil. The seeds then lie dormant until the next wet year, when the desert blooms again.

　　2、Paragraph 3 suggests that during a dry year ephemerals

　　produce even more seeds than in a wet year

　　do not sprout from their seeds

　　bloom much later than in a wet year

　　are more plentiful than perennials

　　PARAGRAPH 2

　　The nature of plant life in deserts is also highly dependent on the fact that they have to adapt to the prevailing aridity. There are two general classes of vegetation: long-lived perennials, which may be succulent (water-storing) and are often dwarfed and woody, and annuals or ephemerals, which have a short life cycle and may form a fairly dense stand immediately after rain.

　　PARAGRAPH 3

　　The ephemeral plants evade drought. Given a year of favorable precipitation, such plants will develop vigorously and produce large numbers of flowers and fruit. This replenishes the seed content of the desert soil. The seeds then lie dormant until the next wet year, when the desert blooms again.

　　3、How is paragraph 2 related to paragraph 3?

　　Paragraph 2 provides a general description of desc plants, and paragraph 3 provides a scientific explanation for these observations.

　　Paragraph 2 divides desert plants into two categories, and paragraph 3 provides further information about one of these categories.

　　Paragraph 2 proposes one way of dividing desert plants into categories, and paragraph 3 explains one problem with this method of classification.

　　Paragraph 2 discusses two categories of desert plants, and paragraph 3 introduces a third category of plants.

　　4、 In saying that ephemerals will develop "vigorously" when there is favorable precipitation, the author means that their development will be

　　sudden

　　early

　　gradual

　　strong

　　healthy

PARAGRAPH 4

　　The perennial vegetation adjusts to the aridity by mear of various avoidance mechanisms. Most desert plants are 11 probably best classified as xerophytes. They possess drought-resisting adaptations: loss of water through the leaves is reduced by means of dense hairs covering waxy leaf surfaces, by the closure of pores during the hottest times to reduce water loss, am by the rolling up or shedding of leaves at the beginning of the dry season. Some xerophytes, the succulents (including cacti), store water in their structures. Another way of countering drought is to have a limited amount of mass above ground and to have extensive root networks below ground. It is not unusual for the roots of some desert perennials to extend downward more than ten meters. Some plants are woody in type — an adaptation designed to prevent collapse of the plant tissue when water stress produces wilting. Another class of desert plant is the phreatophyte. These have adapted to the environment by the development of long taproots that penetrate downward until they approach the assured water supply provided by groundwater. Among these plants are the date palm, tamarisk, and mesquite. They commonly grow near stream channels, springs, or on the margins of lakes.

　　5、The word "countering" in the passage is closest in meaning to

　　eliminating

　　making use of

　　acting against

　　experiencing

　　6、According to paragraph 4, some desert plants with root systems that are extraordinarily well developed have

　　relatively little growth aboveground

　　very leafy aboveground structures

　　nonwoody plant tissue resistant to wilting

　　water stored within their roots

　　7、The word "assured" in the passage is closest in meaning to

　　pure

　　diminished

　　guaranteed

　　deep

　　8、What do "the date palm, tamarisk, and mesquite" have in common?

　　They are always found together.

　　They depend on surface water provided by streams, springs, and lakes.

　　They are phreatophytes.

　　Their roots are capable of breaking through hard soils