代谢性酸中毒根据（）可分为两类，一类为（）的酸中毒，另一类为（）的酸中毒。
参考答案：阴离子间隙；阴离子间隙正常；阴离子间隙增加
已知抛物线与x轴交于点（1，0）和（2，0）且过点（3，4）．求抛物线的解析式．
It costs __ to travel by air as by train. [ ]
A. more three times
B. as much tree times
C. three times as much
