印第安人在公元4~9世纪创造了相当发达的_____文明，其在_____、_____等方面有很大成就。
玛雅；物质文化；科学艺术
联环工应怎样正常操作？
— Why did the police ________ the crowd?
— Because the president's car _________ in the street. [ ]
A. break up,broke down
B. break down, broke down
C. break up, broke up
D. break down, broke up
