单选题 36.   The appearance of the star Gamma Cephei varies regularly. The existence of a planet circling a star can cause regular variation in its appearance. However, the regular variation in Gamma Cephei's appearance is no reason to think that there is a planet circling it, since the slow rotation of a star can also cause its appearance to vary regularly and ______.
    Which of the following most logically completes the argument? ______
    A many stars that have planets circling them rotate slowly
    B. Gamma Cephei varies more in appearance than many other stars do
    C. it is easier to determine the speed at which a star rotates than to determine whether a planet is circling it
    D. analysis of sunspot activity on Gamma Cephei shows that it rotates slowly
    E. Gamma Cephei is only one of many stars that vary regularly in appearance
【正确答案】 D
【答案解析】 D：恒星自转会导致其外表发生变化，同时仙王座伽玛星自身确实会自转，因此可以排除行星公转导致的恒星外表变化，正确。
   A：该选项填到文章内不能进一步证明是因为仙王座伽玛星的自转导致其外表发生变化。
   B：仙王座伽玛星外表变化大无法进一步证明是什么原因。
   C：文章和确定转速的难易程度无关。
   E：文章已经说仙王座伽玛星发生规律变化，至于它是不是唯一的，和文章无关。