继发性腹膜炎的腹痛特点是()
A．阵发性全腹痛
B．逐渐加重的阵发性腹痛
C．持续全腹痛，原发部位显著
D．高热后全腹痛
E．疼痛与进食有关
参考答案：C
已知a为实数，(x+a)10的展开式中x7的系数是-15，则a=（ ）。
My friend likes ______ and ______ very much. [ ]
A. to swim; to run
B. to swim; running
C. swimming; running
D. swimming; to run
