(1) There was an upward trend from 1958 to 1960. Reasons: ① The completion of the "First Five-Year Plan" laid the initial foundation for industrialization. ②The Great Leap Forward directly promoted industrial growth. There was a downward trend from 1960 to 1961. Reasons: ① The Great Leap Forward caused a serious imbalance in the proportion of the national economy. ②The Party Central Committee began to implement the "eight-character policy" and adjust the industry.
(2) Rapid growth from 1976 to 1987.
(3) Enlightenment: Objective economic laws should be followed, and all departments of the national economy must develop in a coordinated manner.