question: What was the problem with manufacturing the tungsten filament ?
answer: Tungsten metal was initially not available in a form that allowed it to be drawn into fine wires .
turker_answer: The problem with manufacturing the tungsten filament was tungsten metal was initially not available in a form that allowed it to be drawn into fine wires .
rule-based: The problem with manufacturing the tungsten filament was tungsten metal was initially not available in a form that allowed it to be drawn into fine wires .