crystal ball
noun [ C usually singular ] uk/ˌkrɪs.təl ˈbɔːl/ us/ˌkrɪs.təl ˈbɑːl/
（可预言未来的）水晶球
a transparent glass ball used by someone who says they can discover what will happen to you in the future by looking into it
Looking into the crystal ball, it's safe to say that interest rates will rise next year. 预测一下未来，可以很明确地说明年利率会上升。