Tina sold her car __________ because the car was too old and broken .
A:at a high price
B:at a low price
C:at an expensive price
D:at a cheaply price
它是1898年中国最轰动的出版物,介绍了达尔文的进化论思想,提出了“物竞天择,适者生存”的观点。它是( )
跨越代沟的最好方式是( )
设等比数列{an}的公比q=2,前n项和为Sn,则 S3a2 =( )