郊游的时候，下面哪种做法是留住美好记忆的正确方式？（）A.照相

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问题单项选择题

郊游的时候，下面哪种做法是留住美好记忆的正确方式？（）

A.照相留念

B.在树木上刻自己的名字

C.乱扔垃圾

D.随地大小便

答案

参考答案：A

选择题

某V ml Al₂(SO₄)₃溶液中含a g Al³⁺，取出V/4 ml溶液稀释成 4V ml，则稀释后溶液的SO₄²^－的物质的量浓度是( )

A．125a/9V mol/L

B．125a/18V mol/L

C．125a/36V mol/L

D．125a/54V mol/L

单项选择题

Which of the following is TRUE about the call feature of a bond It:（）

A. stipulates whether and under what circumstances the bondholders can request an earlier repayment of the principal amount prior to maturity.

B. describes the credit risk of the bond.

C. stipulates whether and under what circumstances the issuer can redeem the bond prior to maturity.