[填空题]
A nature photographer wishes to/+emvnj2o b7 a,fz (n2m6rsh i photograph a 28b8l g a,,e-gbll -mksol3 vj,7-mtall tree from a distance of 58 ml-3 g7lg,kv-beabjl , osm8,l. What focal-length lens should be used if the image is to fill the 24-mm height of the film? mm
