求问GWD第一套Q27

starry1007

回原文定位： However, when diatoms are
    observed under constant conditions
in a laboratory, they still display
periodic behavior, continuing to bur-
(25)    row on schedule for several weeks.
但是凭什么认为several weeks 就是short term啊，在做实验的情况下不是也很长了嘛？实验总有个结束的时候啊！