[[20-3]] se enciende, 'is lighted.' Note how often, in this story, the reflexive is best translated by the English passive.
[[20-6]] de, 'in' (as often, when used with manera).
[[20-13]] tienen que, 'have to,' or 'must.'
[[20-20]] No se podía atravesar, 'it was impossible to pass over.'
[[20-21]] al día, 'a day.'
21.—[[21-5]] Sabiendo ellos, 'since they knew.' Note that the pres. part. usually precedes its subject.
[[21-6]] habían de pasar, 'would pass,' or 'were to pass' (habían de pasar is almost equivalent to pasarían).
[[21-10]] Llegado que hubo=luego que hubo llegado.
[[21-11]] le ataron de pies, 'they tied his feet.'