{HEAD ~ The primary objective} of the present invention is to provide {TAIL ~ a bidirectional projector}, which may project slides onto two screens in the same time 
is to provide
{ HEAD ~ The primary objective } of the present invention is to provide { TAIL ~ a bidirectional projector } , which may project slides onto two screens in the same time
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH