A curve is a line no part is straight and which has no angle.
A. that
B. whose
C. in which
D. of which
网友回答
A. that
B. whose
C. in which
(答案→)D. of which
解析：句意：曲线是一条线它没有部分是直的而且没有角。这里是定语从句先行词是a curve，定语从句中是no part of the curve is straight，所以缺少介词of+关系代词（which），所以选D.