题目

下列反应中既为化合反应又为氧化反应的是   A．水氢气+氧气        B．镁+氧气氧化镁   C．水+二氧化碳→碳酸      D．酒精+氧气水+二氧化碳 答案：B –Where is your father, Ted?-He _______ Shanghai on business. He ________ there many times.A. has gone to, has gone toB. has gone to, has beenC. has been to, has been to