设备招标文件一经发出，招标单位不得随意修改或增加附加条件，如确需修改和补充，一般应在

在汇入门静脉的血液中，来自脾的血液约占：（）。

A.25%

B.15%

C.10%

D.5%

E.20%

发票种类的划分，由国家税务总局确定。( )

生命活动中能量的直接供体是

A．葡萄糖
B．脂肪酸
C．氨基酸
D．磷酸肌酸
E．三磷酸腺苷

下列对象不属于ADO对象模型的是( )。

A．Connection

B．Workspace

C．RecOrdSet

D．Command

Last year, an appliance store sold an average (arithmetic mean) of 42 microwave ovens per month. In the first 10 months of this year, the store has sold an average (arithmetic mean) of only 20 microwaves per month. What was the average number of microwaves sold per month during the entire 22-month period

A．21

B．30

C．31

D．32

E．(E) 44