说明：  用运算放大器做正弦波振荡器在学校时老师就教过，应该是一个常用的电路。现在我做了几款，实际效果都 不理想。哪位做过，可否透露些经验或成功的电路？
(Operational amplifier with sinusoidal oscillator do teachers teach in schools that should be a commonly used circuit. Now I have done a few, the actual results are far from satisfactory. Which done, tell us more experience or success of the circuit?)