分析数据时，为了能清楚地反映事物地变化情况，可以选择______统计图；为了能清

如图所示电路，电阻R₁的值为20Ω，当开关S₁闭合，开关S₂断开时，电压表的读数为3.0V，当开关S₁闭合，开关S₂闭合时，电压表的读数为2.0V，电压表的内阻足够大．求：

(1)电源的电动势E是多大?

(2)电源的内电阻r是多大?

(3)当电压表的读数为2.0V时，电阻R₁上消耗的电功率P是多大?

传染性单核细胞增多症是由哪种病毒所引起的淋巴细胞增生性急性自限性传染病（）

A.单纯疱疹病毒Ⅰ型

B.巨细胞病毒

C.EB病毒

D.水痘-带状疱疹病毒

E.单纯疱疹病毒Ⅱ型

灭多威乳油外观是怎样的？

No Errors Printing has entered into a "plain-vanilla" interest rate swap on $1000000 notional principal. No Errors receives a fixed rate of 5.5 percent on payments that occur at quarterly intervals. Platteville Investments, a swap broker, negotiates with another firm, Perfect Bid, to take the pay-fixed side of the swap. The floating rate payment is based on LIBOR (currently at 6.0 percent). Because of the current interest rate environment, No Errors expects to pay a net amount at the next settlement date and has created a reserve to cover the cash outlay. At the time of the next payment ( due in exactly one quarter), the reserve balance is $1000. To fulfill its obligations under the swap, No Errors will need approximately how much additional cash

A．

B．

C．