已知Sn是数列{an}的前n项和,Sn=2n-1,则a10= ( )
A:256
B:512
C:1024
D:2048
图中能使腐烂的水果散发出酒味的微生物是( )
——Hello! Would you like to go to the party with me tonight?
——I'm sorry I can't . Mother won't ______me to go out in the evening.
体育委员小金带了500元钱去买体育用品,已知一个足球x元,一个篮球y元.则代数式500﹣2x﹣3y表示的实际意义为____ .