什么是电流源？
参考答案：
由一个固定电流IS和一个内电导G0并联支路所组成的等效电源称为电流源。
不需要与急性结石性胆囊炎进行鉴别的是（）
A.急性胰腺炎
B.高位急性阑尾炎
C.消化性溃疡穿孔
D.肝脓肿
E.急性单纯性肠梗阻
The beef I ate at the restaurant yesterday is delicious. I'd like to have it again even if it costs（）
A.as wice much
B.much as twice
C.as much as
D.twice as much
