题目观察下面的一列单项式:−x2-\frac{x}{2}−2x,x2x^{2}x2,−2x3-2x^{3}−2x3,4x44x^{4}4x4,−8x5-8x^{5}−8x5,…\ldots…,根据其中的规律,得出第777个单项式是（ ）A.−32x7-32x^{7}−32x7B.32x732x^{7}32x7C.−64x7-64x^{7}−64x7D.64x764x^{7}64x7知识点：单项式章节：未标注
