当泥浆滤液矿化度与地层水矿化度大致相等时，自然电位偏转幅度（）。
A.很大
B.很小
C.急剧增大
D.不确定
参考答案：B
简述布鲁纳对发现教学的教学设计提出的四项原则。
-What makes her so frightened?
-Oh, it is the mouse that she ___ on her bad while looking for her watch．[ ]
A. came about
B．came across
C．came through
D．came up
