请教2道GWD的题

1. Seldom more than 40 feet wide and 12 feet deep, but it ran 363 miles across the rugged wilderness of upstate New York, the Erie Canal connected
2. Seldom more than 40 feet wide or 12 feet deep but running 363 miles across the rugged wilderness of upstate New York, the Erie Canal connected
3. It was seldom more than 40 feet wide and 12 feet deep, and ran 363 miles across the rugged wilderness of upstate New York, but the Erie Canal, connecting
4. The Erie Canal was seldom more than 40 feet wide or 12 feet deep and it ran 363 miles across the rugged wilderness of upstate New York, which connected

    E.The Erie Canal, seldom more than 40 feet wide and 12 feet deep, but running 363 miles across the rugged wilderness of upstate New York, connecting

答案是B我选的A,but 后面不是一般加完整的句子吗?

1. year, but only if non-OPEC nations, including Norway, Mexico, and Russia, were to trim output
2. year, but only if the output of non-OPEC nations, which includes Norway, Mexico, and Russia, is trimmed
3. year only if the output of non-OPEC nations, including Norway, Mexico, and Russia, would be trimmed
4. year only if non-OPEC nations, which includes Norway, Mexico, and Russia, were trimming output

    E. year only if non-OPEC nations, including Norway, Mexico, and Russia, trim output

答案是E我选的C

请问Only if 后面除了用完成式还有哪些用法?

第一题　前面　的 Adj but doing, 都是修饰后面的 canal，

一般ＢＵＴ前后如果主语一致，　应该可以省略

第二题 only if 加一般现在，　而且Ｃ是被动哦，　太烦了,

谢谢楼上但是：

1.but it ran为什么Ａ中用ran,而but runningＢ中却用running

并且Ａ．Seldom more than 40 feet wide and 12 feet deep

Ｂ．Seldom more than 40 feet wide or 12 feet deep ？？一个用and 一个用or?

2.only if 是可以加完成式，那还可以加什么形式呢？有什么特点？

有效性和准确性的问题，A肯定不准确，然后or和and的意思又不同，不一定要同等宽高

seldom表示否定的意思

所以应该用or而不是and

就像I seldomly drink or smoke

running做伴随状语阿，修饰canal