患者，男性，65岁，有慢性肾衰竭，因腰椎间盘突出行手术治疗。

该患者手术后恶心、呕吐的常见原因是（）

A.术后体位不适或不习惯

B.电解质紊乱

C.肠梗阻

D.切口疼痛

E.麻醉药物

—I don’t think it very expensive to buy a family computer here.

—Really? I’ll buy _____ next week.

A．it

B．this

C．one

D．mine