如图所示,两电阻R1=R2,电源电压相同,要使甲、乙两电路图中产生的总热量相等,则所需时之比t甲:t乙为( )
A.4:1
B.1:4
C.2:1
D.1:2
答案:A
后颅窝手术中,切开枕骨大孔后缘一般限制在中线旁1.5cm内,主要是为避免损伤()
A.延髓
B.小脑扁桃体
C.上颈髓
D.,椎动脉
E.环窦
Li Lei likes ______ mooncakes ______ nuts in them. [ ]
A. eat, with
B. eating, for
C. to eat, for
D. eating, with