2017届高考英语二轮阅读理解训练：（21）

　　2017届高考英语二轮专题训练：阅读理解（21）

　　A

　　Butterfly gardens can be grown throughout the United States.There is a wide variety of both butterfly­attracting (nectar) plants and host plants covering climate zones throughout the country.Butterfly gardens can range

　　in size from a few containers placed in a sunny spot to several acres.

　　Nectar­producing (产蜜的) plants will attract butterflies to your garden.In order to support a full butterfly life cycle，host plants (for laying eggs and used as a caterpillar food source) must also be present.

　　Throughout the country，the general requirements

　　for butterfly gardening are the same：full sun，nectar source plants，larval (幼虫的)

　　host plants，a pesticide­free environment，and knowledge of the local butterfly

　　species.Many butterfly­attracting plants are natives and require little attention，as they are naturally adapted to the region in which they live.

　　Butterfly gardens are best planted in spring with younger plants or in fall with mature plants that will become dormant quickly and re­emerge in

　　spring.It is best not to plant in the heat of summer or the cold of winter.

　　One of the most common mistakes in butterfly gardening is planting only one nectar source.Adult butterflies have a very short lifespan.Planting a variety of nectar sources will encourage more butterflies to visit the garden.Planting an adequate supply of host plants gives butterflies a place to lay their eggs，which will successfully hatch (孵化) and result in butterflies that will continue to visit the garden.