眉头一皱，计上心来

Explanation: Described as a thinking strategy, suddenly came up with an idea. 　　Usage: Complex sentence; for clause; that suddenly came up with an idea 　　Source: Yuan Ji Junxiang "Orphan of Zhao" Second off: "Why Suicide Han Jue, and must take the Orphan of Chao, Zensheng good? Frowned, namely, upper center to!" 　　Examples: "Three Kingdoms" on the so-called "~", we say common so-called "let me think about" is used in the concept of mind in judgments and reasoning for the effort. (Mao Zedong's "On Practice"