简述多元化战略的正效应。
参考答案：
（1）内部优势效应；（2）风险分散效应；（3）协同效应；（4）范围经济效应；（5）信息优势效应。
推焦前先打开上升管和一个装煤孔盖，其目的是烧掉炉顶空间的石墨。
Signs and symptoms of retinal detachment include which of the following
A．Painless decrease in vision, a veil over the visual field, and flashing lights.
B．A veil over the visual field, increased intraocular pressure, and yellow-green halos around visual images.
C．Photophobia, yellow-green halos around visual images, and blurred vision.
D．Unilateral eye inflammation, a cloudy cornea, and a moderately dilated pupil.
