山区公路建设中应遵循的原则是 [ ]
A．尽可能连接居民点
B．在山谷中应避开陡坡
C．在陡坡段增加“之”字形弯曲
D．尽可能避免跨越河流
BC
He is a _____ teacher, and he explains every problem to his students with great _____. [ ]
A. patiently; patience
B. patiently; patient
C. patient; patience
D. patient; patient
电磁感应定律是感应电势的大小和磁通所链的（）和（）成（）。
