高阻接地故障发射为正脉冲，反射波形有何特点？
参考答案：
反射波形为前沿有负反冲的正脉冲。
The day after tomorrow they ______ a volleyball match. [ ]
A. will watching
B. watches
C. is watching
D. are going to watch
免疫组织化学染色，淀粉酶阳性的涎腺肿瘤是
A．多形性腺瘤
B．嗜酸性腺瘤
C．腺样囊性癌
D．腺泡细胞癌
E．粘液表皮样癌
