1.The density in summer get to the tip of the year(204.62×104 ind. /L) and that in the autumndecline to the lowest level(72.54×104 ind. /L) while we can know the zone dis-tribution(Ⅲ>Ⅰ>Ⅱ) .
2.On one of those sober and rather melancholy days in the latter part of autumn when the shadows of morning and evening almost mingle together, and throw a gloom over the decline of the year, I passed several hours in rambling about Westminster Abbey.
