什么是频率联络线功率偏差控制？
参考答案：
按照频率偏差又按照联络线交换功率进行调节，维持各地区电力系统负荷波动的就地平衡。
Rapid application development (RAD) systems purport to lighten the developer’s (46) by making it easy to program an application with simple intuitive steps. RAD tools (47) the developer everything needed to construct a fully functional application quickly and easily. They make short work of modifying the developed product to (48) changes after the program is finished. Applications developed with RAD tools are constructed as they are envisioned. As an application’s real usefulness (49) , the developer armed with RAD tools should be able to (50) on new features with little fuss.
A. appearances B. emergesC. recognizes D. solves
设非齐次线性微分方程y’+P（x）y=Q（x）有两个不同的解：Y1（x）与y2（x），C为任意常数，则该方程的通解是（）．
A.
B.
C.
D.
