20世纪30年代的世界主要矛盾是( )
John shut everybody out of the kitchen ______ he could prepare his grand surprise for the party.
如图是一个算法的流程图,若输出的结果是31,则判断框中整数M的值是( )
定义运算abcd,则符合条件z1+2i1-i1+i的复数z为( )