五行中的火水的关系是（）。A、相生B、相克C、相乘D、相侮

试举一例，说明“两个无理数的差仍是无理数”是错误的：______．

Ali is a dealer in Persian rugs. As his business has been rather slow, he placed an advertisement in the Saturday edition of his local paper stating:‘Once in a lifetime opportunity to own a handmade Persian antique rug for only ￡1,500 – cash only. This is a serious offer – the rug will go to the first person who accepts it – offer valid for one day only – today Saturday.’When Bud saw the advert, he immediately posted a letter of acceptance of Ali’s offer in order to make sure he got the rug.Cil also saw the advert and after inspecting the rug offered Ali a cheque for ￡1,500, but he refused to accept the cheque and told her she could not have the rug.Later in the day, Das asked Ali if he would keep the offer open until he could get to his bank to arrange a loan. Ali agreed, but subsequently, when Ed offered to pay ￡2,000 in cash for the rug, Ali sold the rug to him.On Monday morning Bud’s letter arrived, and Das returned to complete his purchase of the rug.Required:In the context of the rules governing the creation of contracts, advise:

(d) whether Das has any right of action against Ali. (2 marks)

在电感元件组成的电力系统中发生短路时，短路的暂态过程中将出现随时间衰减的周期自由分量，

患者，男性，41岁，近半年来反复发生左上肢抽动，每次约半分钟自行缓解。最可能的诊断是（）

A.单纯部分发作

B.肌阵挛发作

C.自动症

D.小舞蹈病

E.低钙性手足搐搦

纬度地带性分布规律