—Because she wondered _____.
A：when would the policeman come
B：if had her students survived the earthquake
C：how she could get to the station
D：where did the other students go
设P={x|x2﹣2x﹣3≤0}，a= 2 ，则下列关系中正确的是（ ）
菜豆种子的胚是由（ ）组成的．
1927年，蒋介石、汪精卫先后背叛革命，导致革命统一战线破裂，国民大革命失败。它给共产党留下的最为深刻的教训是
①提出和平共处五项原则
②恢复在联合国的合法席位
③中日正式建立外交关系
④恢复与苏联的友好交往
