星形细胞瘤的CT表现为
A.不规则低密度B.囊样低密度C.可强化D.可不强化E.以上都是
参考答案:E
—Have you worked here since you graduated?
—No, I ________ at a factory in Beijing for six years.
A.would work
B.have worked
C.had worked
D.worked
论述冷战结束后南北经济关系的变化和特点。