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.
A. the sandpipers vanishing in the northeastern United States is a result of residential and industrial development and of changes in
B. the bird itself is vanishing in the northeastern United States as a result of residential and industrial development and of changes in
C. that the birds themselves are vanishing in the northeastern United States is due to residential and industrial development and changes to
D. in the northeastern United States, sandpipers’ vanishing is due to residential and industrial development and to changes in
E. in the northeastern United States, the sandpipers’ vanishing, a result of residential and industrial development and changing
答案B，不知道itself 和it 是否可以指代不同的东西，在这里it应该指代的是sandpiper 吧 | 
