单选题 .  If you are like most people, your intelligence varies from season to season. You are probably a lot     1    in the spring than you are at any other     2    of year. A     3    scientist, Elisworth Huntington,     4    from other men's work and his own     5    peoples in different climates that climate and temperature have a(n)     6    effect on our mental abilities.
    He found that cool weather is much more     7    for creative thinking than is summer     8    This does not mean that all people are     9    intelligent in the summer than they are during the     10    of the year. It does mean,     11    , that the mental abilities of large     12    of people tend to be     13    in the summer.
    Spring appears to be the best period of the year for     14    . One reason may be that in the spring man's mental abilities are     15    by the same factors that     16    great changes in all nature.
    Fall is the     17    best season, then winter.     18    summer, it seems to be a     19    time to take a long     20    from thinking.1.