[填空题]The work for which Thomas Malthus is still most widely known is his Essay on the Principle of Population, which first appeared in 1798. This book introduced Malthus’s __67__ that population inescapably outgrows subsistence (生活资料), and that this difference __68__ population size and the ability to adequately meet the __69__ subsistence needs of all the members of that population " naturally" produces a fundamental struggle for __70__ in which some flourish at the __71__ of others. Charles Darwin’s most important contribution __72__ the field of biology, described in his work. On the Origin of Species, was to __73__ Malthus’s observation that plants and animals multiply faster than nature can provide for them to his own __74__ of the process of "evolution" - the notion that different forms of life develop __75__ from a common ancestry (祖先). Combining these elements, Darwin __76__ that the factors of "the struggle for existence" and "the survival of the fittest" are the central mechani
A. A．from
B．on
C．at
D．in

[填空题]The work for which Thomas Malthus is still most widely known is his Essay on the Principle of Population, which first appeared in 1798. This book introduced Malthus’s __67__ that population inescapably outgrows subsistence (生活资料), and that this difference __68__ population size and the ability to adequately meet the __69__ subsistence needs of all the members of that population " naturally" produces a fundamental struggle for __70__ in which some flourish at the __71__ of others. Charles Darwin’s most important contribution __72__ the field of biology, described in his work. On the Origin of Species, was to __73__ Malthus’s observation that plants and animals multiply faster than nature can provide for them to his own __74__ of the process of "evolution" - the notion that different forms of life develop __75__ from a common ancestry (祖先). Combining these elements, Darwin __76__ that the factors of "the struggle for existence" and "the survival of the fittest" are the central mechani
A. A．scheme
B．reference
C．theory
D．illusion