The research and development in information and data retrieval i

The research and development in information and data retrieval is aimed 31_____ improving the effectiveness and efficiency of retrieval. Individual and parallel development 32_____ database management systems has left this sector 33_____ a centralized vision and coordination 34_____ the different types of search engines. Search engines 35_____ the Internet are very specific and not able to cope with multiple database formats and file types.
33.
【正确答案】：without