[填空题]
A converging lens with focal length of 10.0 cm is placed in contact with a ducx g/ *nrd46ziver4/c gd nru6x*zc/dz1 6*)x1s iiwejtuging lens with a focal length of -20.0 cm. What isstidj1)/cw6ieu z *x1 the focal length of the combination, and is the combination converging or diverging? cm (converging)
