男,30岁,左下腹痛伴脓血便半个月。查体腹部无异常。检查方法首选()。
A.大便常规+培养
B.B超
C.钡灌肠
D.全程钡剂
E.全结肠镜检
参考答案:A
Although the causes of cancer_____, we do not yet have any practical way to prevent it.
A.are being uncovered
B.have been uncovering
C.are uncovering
D.have uncovered
反射密度仪适合测量()。
A、实地密度
B、图文重影
C、墨层厚度
D、油墨乳化