Make sure that the intensity of the reticle light decreases gradually to zero.确保十字线光的强度逐渐 降低到零。
A.Make sure that the brightness of the reticle light rapidly drops to zero. B.Make sure that the intensity of the reticle light lessens radically to zero. C.Make sure that the brightness of the reticle light is gradually reduced to zero.正确答案C
