已知某机器一个稳定运动循环内的等效阻力矩M_VC-φ曲线如图所示，等效驱动力矩为常数。并知等效构件的最大角速度为ω_max=200rad/s，最小角速度为ω_min=180rad/s。

试求：

(1)等效驱动力矩M_va的值。

(2)当不计其余构件的转动惯量时，飞轮的转动惯量J_F的值。

An analyst does research about probabilities of a fund and an index. The fund underperforms the index, given the index return is positive is 0.45. The fund underperforms the index and the index return is positive is 0.20. If the two events "the fund underperforms the index" and "the index return is positive" are independent, the probability that the fund underperforms the index or the index return is positive is closest to:（）

A. 0.44

B. 0.69

C. 0.89