5.False

　　See para.5：for the past million years， ice ages have occurred roughly every 100，000 years.Before that， they occurred roughly every 41，000 years.

　　6.False

　　See para.7：“In Milankovitch， there is certainly no good idea why the frequency should change from one to another，” ...Nor is the transition problem the only one the Milankovitch theory faces.

　　7.Not Given

　　See para.8：if sea ice begins to form because of a slight cooling， carbon dioxide?is locked into the ice.That weakens the greenhouse effect.(The passage doesn抰 mention anything about locking Co2 into ice artificially.)

　　8.True

　　See para.9：there is no lack of such mechanisms.“If you add their effects together， there is more than enough feedback to make Milankovitch work，”?“The problem now is identifying which mechanisms are at work.” This is why scientists like Edwards are not yet ready to give up on the current theory.

　　9.True

　　See the sentences in para.9 (According to Edwards， 卙e says.“I can’t see any way of testing [Ehrlich‘s] idea to see where we are in the temperature oscillation.”) and para.10 (Ehrlich concedes this.“If there is a way to test this theory on the sun， I can’t think of one that is practical).

　　10.constant

　　See para.2：According to the standard view， the temperature of the sun‘s core is held constant by the opposing pressures of gravity and nuclear fusion.

　　11.orbit

　　See para.6：Most scientists believe that the ice ages are the result of subtle changes in Earth’s orbit， 匛arth‘s orbit gradually changes shape from a circle to a slight ellipse and back again roughly every 100，000 years.

　　12.instabilities

　　See para.3：?i style=’