單項(xiàng)選擇題

圖示電路是集成計(jì)數(shù)74LS161構(gòu)成的可變進(jìn)制計(jì)數(shù)器。試分析當(dāng)控制變量A 為1和0時,電路各為幾進(jìn)計(jì)數(shù)器?()

A.A=1時為十二進(jìn)制計(jì)數(shù)器,A=0時為十進(jìn)制計(jì)數(shù)器
B.A=1時為十一進(jìn)制計(jì)數(shù)器,A=0時為十進(jìn)制計(jì)數(shù)器
C.A=1時為十進(jìn)制計(jì)數(shù)器,A=0時為十二進(jìn)制計(jì)數(shù)器
D.A=1時為十進(jìn)制計(jì)數(shù)器,A=0時為十一進(jìn)制計(jì)數(shù)器