已知函数f（x）=3sin2x-2cos2x-1，x∈R，f（x）在△ABC中，

An investor entered into a margin purchase transaction. He purchased on margin 100 shares of stock priced at $ 60 per share. The investor borrowed the maximum amount allowed by the initial margin requirement of 50 percent, and the maintenance margin is 30 percent. Under the requirement of margin purchase, the lowest price per share at which the stock could sell before the investor would receive a margin call is closest to:()

A. $30.

B. $40.

C. $43.

我国上海期货交易所的黄金期货合约的交易代码是（）。

A.CU

B.AL

C.ZN

D.AU

根据检疫机构签发的产地证书是进口国海关征收或减免关税的有效凭证( )

设某汉字的区位码为（2710）D，则其（）。

A.国标码为（4730）H

B.国标码为（3B2A.H

C.机内码为（BBAA.H

D.机内码为（9B8A.H

患者因龋坏一次充填后，冷热痛，去除刺激可恢复，但无自发痛。以下哪项不是造成牙冷热痛的原因（）

A.充填未垫底

B.诊断失误

C.充填材料不当

D.充填材料选择不当

E.充填体悬突