题目

我国的国土面积为9597000平方千米，把9597000保留三个有效数字，并用科学记数法表示为  A． B．      C．    D． 答案：BThe little girl         ,but her family was too poor at that time. A.could go to school B.could have gone to school C.must have gone to school　 D.can have gone to school