A:for; could have bee
B:with; should have bee
C:at; could have bee
D:from; may have bee
已知向量 p=(1,2),q=(x,3) ,若 p⊥q ,则 |p+q|= ____.
①求证:△ABE≌△CBD;
②若∠CAE=30°,求∠BDC的度数.
19世纪晚期,某西方报纸称:“甲午以后,中国有三党,守旧党……意在保现存之局面;中立党……意在保国以变法;维新党……意在以作乱为自振之机。”文中所指的维新党是