__ of them ___ having a good time at the party.[ ]

A. Everyone, is  

B. Everyone, are  

C. Every one, is  

D. Every one, are

以下关于胎儿血循环的叙述错误的是

A．供应上肢的血液的氧含量较卜半身的高
B．从胎盘来的动脉血经脐动脉进入胎儿体内
C．肺处于压缩状态
D．右心房的血可经卵圆孔进入左房
E．动脉导管开放