不属于Spee曲线特点的是（）

A．为下颌牙列的纵拾曲线

B．形成一条向下凹的曲线

C．连接下颌切牙嵴、尖牙牙尖及前磨牙、磨牙的颊尖

D．在切邪恶段较平

E．自尖牙起向后逐渐降低，到第二磨牙远中颊尖处最低

What was one of the main reasons for the change in architectural style in eighteenth century North America a. More architects arrived in the colonies. b. The colonists developed an interest in classical architecture. c. Bricks were more readily available. d. The colonists had more money to spend on housing.