根据课文内容填空(每空不限词数；共6个空格，每空格1分，满分6分)
NCE 47
We keep trying all four methods, but the         we produce worldwide            .
NCE 48
We expected the path       , but we found that it       through the trees.
NCE 49
…, but Bessie seemed unable         . She           and kept mumbling about the guests.