问题 选择题
雨季乌云滚滚,常有雷电发生,这是因为(  )

A.乌云滚滚,摩擦生热

B.带有相同电荷的云团相遇相互作用

C.乌云将积蓄的大量太阳能一下子释放出来

D.带有异种电荷的云团之间或云团与地面之间产生放电现象

答案

答案:D

问答题

新民主主义革命时期,国共两党两度合作。两次合作的主要任务是什么?并分别说明两次合作的结果。

                                                                                                                                                            

                                                                                                                                                            

                                                                                                                                                            

                                                                                                                                                            

                                                                                                                                                            

单项选择题