一叶知秋----The falling of one leaf heralds the autumn
例句:
A: It’s said that he can forecast things in future.
听说他能够预知未来。
B:That’s because he knows well that the falling of one leaf heralds the autumn.
那是因为他善于一叶知秋。
同义词:
It is a straw in the wind. A small sign can indicate a great trend.
v. 显示,象征,指示
v. 指明,表明