The research conducted by Porter and Landfield shows that．
A. changes in the levels of adrenal hormones have nothing to do with brain aging
B. changes in the levels of adrenal hormones may affect brain aging．
C. chronic stress may strengthen a man’s memory．
D. maybe damaged．
A．variousB．heartC．cardiovascular D．multiple
A. various
B. heart
C. cardiovascular
D. multiple
When the levels of cortisol go higher，the hippocampus in the brain may．
A. become larger．
B. become smaller．
C. disappear completely．
D. be totally damaged．
A．whichB．thatC．somethingD．anything
A. which
B. that
C. something
D. anything
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