题目内容：
请阅读下面材料，完成第小题。Greenspace facilities are contributing to an important extent to the quality of the urban environ．ment.Fortunately it is no longer necessary that every lecture or every book about this subject has to start with the proof of this idea．At present it is generally accepted，although more as self-evident statement than on the base of a closely-reasoned scientific proof．The recognition of the importance of greenspaces in the urban environment is a first step on the right way，this does not mean，however，that sufficient details are known about the functions of greenspace in towns and about the wav in whichthe inhabitants are using these spaces．As to this rather complex subject I shall．within the scope ofthis lecture，enter into oBe aspect only namely the recreatire function of greermpace faeihties．
The theoretical separation of living，working，traffic and recreation which for many years has been used in town-and-country planning，has in my opinion resulted in disproportionate attention for forms of recreation far from home，whereas there Was relatively little attention for improvement of rec-reative possibilities in the direct neighborhood of the home．We have come to the conclusion that this is not right，because an important part of the time which we do not pass in sleeping or working，is used for activities at and arOund home．So it is。bvi。us that recreation in the open air has to begin at the street-door of the house．The urban environment has to offer as many reereation activities as pos．sible，and the design of these has to be such that more obligatory activities can also haye a recreative aspect．
The very best standard of living is nothing if it is not possible to take a pleasant walk in the dis-trict，if the children cannot be allowed to play in the streets，because the risks of traffic are too great．if during shopping you can nowhere find a spot for enjoying for a moment the nice weather，in short，if you only feel yourself at home after the street-door of your house is closed after you．
According to the author．the importance of greenspaces in the urban environment__________． A．is still unknown
B．is usually neglected
C．is being closely studied
D．has been fully recognized
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