27. ________ in the mountains for a week, the two students were finally saved by the local police (A) Having lost (B) Lost (C) Being lost (D) Losing

29.They _______ on the program for almost one week before I joined them, and now we________ it as no good results have come out so far. (A) had been working; are still working (B) had worked; were still working (C) have been working; have worked (D) have worked; are still working