Given that Czech doesn't have articles there isn't a direct equivalent of 'the' and 'ten' often seems to be used where English would use 'the'. Similarly 'nějaký' is often used where English would use 'a' - for Czech learners of English it often means they overuse 'some'.
This DL program is quite consistent: 'ten/to/ty' etc is always translated as either "that" or "the", never as "this".
Furthermore, when a bare noun, with no determiner in front of it, appears in the Czech sentence, this program is consistent in allowing you to insert the indefinite article "a" into the English translation, but not the definite article "the". In short, if no determiner in the Czech, then no "the" in the English.
The one exception to the above that I've noticed has to do with possessive constructions. For example, in addition to "the doctor's office", DL will allow (as indeed it should) "the office of the doctor", even when the Czech original has no demonstrative corresponding to the first "the" in "the office of the doctor".