He and his mother ______ at home last night. [ ]
A. are
B. is
C. was
D. were
答案:D
代谢性酸中毒血钾浓度往往升高。()
算术运算符的优先级按下面次序排列:++和--的级别最高,然后是______和/以及%,而+和—的级别最低。