题目

常温下，有两种溶液：①0.1 mol·L−1 CH3COOH溶液  ②0.1 mol·L−1 CH3COONa溶液。 (1)溶液①的pH______7(填“大于”、“小于”或“等于”)，醋酸电离平衡常数Ka=            (表达式)。 (2)溶液①②等体积混合后溶液呈______性，混合溶液的物料守恒关系为：________________________________。 (3)下列说法正确的是________(填序号)。 a．两种溶液中c(CH3COO−)都小于0.1 mol·L−1 b．两种溶液中c(CH3COO−)都等于0.1 mol·L−1 c．CH3COOH溶液中c(CH3COO−)小于CH3COONa溶液中c(CH3COO−)A Policeman and a Thief  One day a policeman was taking a thief to the city . On the way , they saw a shop . The thief said . “ Let me go into the shop to buy some bread . We can eat it in the train . ”The policeman agreed . The thief went into the shop and ran out of the back door . When the policeman knew that , he began to look for the thief everywhere . At last the policeman caught(抓获) thief again . They went on to the city . On the way they came to the same shop . The thief wanted to buy some bread again . “Oh , no . ” said the policeman , “You did that before , and you ran away . This time I’ll go into the shop and buy bread . You must wait here for me . ”1.What was the policeman doing one day ?A.Catching a thief with others .B.Doing nothing.C.Taking a thief to the city .D.Walking go the city by himself .2.On the way the thief asked to         . A.buy some food to eat .B.let him free .C.take a rest .D.walk slowly .3.When the thief went into the shop , he ran out of        .A.the back door .B.the back window .C.the front door .D.the front window .4.When the thief ran away the first time , what did the policeman do ?A.The policeman caught the thief again .B.The policeman looked for the thief . but he didn,t find him .C.The thief was caught again by other policemen .D.The policeman went back without(没有) the thief .5.From the last three sentences, we know that the policeman was very        .     A.braveB.carefulC.cleverD.foolish