Q13:
Like the grassy fields and old pastures that the upland sandpiper needs for feeding and nesting when it returns in May after wintering in the Argentine Pampas, the sandpipers vanishing in the northeastern United States is a result of residential and industrial development and of changes in farming practices.
the sandpipers vanishing in the northeastern United States is a result of residential and industrial development and of changes in
the bird itself is vanishing in the northeastern United States as a result of residential and industrial development and of changes in
that the birds themselves are vanishing in the northeastern United States is due to residential and industrial development and changes to
in the northeastern United States, sandpipers’ vanishing is due to residential and industrial development and to changes in
in the northeastern United States, the sandpipers’ vanishing, a result of residential and industrial development and changing
请教大家.我选了d 答案是b
我看不懂.主语不同啊. | 
