选用（）作为载气，可以使TCD检测器设定更大的桥流值。
A、氦气
B、氮气
C、氩气
D、二氧化碳
参考答案：A
They were __________ admision to the military exhibition because they were foreigners.
A．denied
B．declined
C．deprived
D．rejected
评价急性胰腺炎患者胰腺坏死的最佳手段是（）
A.腹腔穿刺
B.腹部B超
C.平扫腹部CT
D.增强腹部CT
E.血清生化学
