A:①②
B:①③
C:②③
D:②④
下列对东欧剧变实质理解正确的是( )
His parents were worried that he______ too much time chatting on line.
Last night, I _______ computer games when my mother came into my bedroom. You can't imagine how embarrassed I was then!
∠E=30°,则∠F=____.
已知四边形ABCD,从下列条件中:(1)AB∥CD;(2)BC∥AD;(3)AB=CD;(4)BC=AD;(5)∠A=∠C;(6)∠B=∠D.任取其中两个,可以得出“四边形ABCD是平行四边形”这一结论的情况有( )