68. The holly plant has more spines on the lower leaves because most animals________. (A) are not tall enough (B) like the lower leaves only (C) are not clever enough (D) can get the lower leaves easily

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