两道SC问题

redli

1）repelled by bodily punishments such as maiming and branding, (the idea of penitentaiaries were reforms of the penal system by Quakers.)
c)Quakers suggested the penitentiary as a reform of the penal system.
d)Quakers suggested that the penal system be reformed as penitentiaries .
问题：选C，为什么D不可以，错在哪里？

2)For some birds the sense of smell appears to play a role in navigation, since pigeons with surgically removed olfactory nerves (were found to have increased difficulties) in homing.
B)have been found to have increased difficulty.
问题：选B，原句错在哪里？为什么一定用过去完成时，DIFFICULTY一定要用单数。

开若兰

QUOTE:

以下是引用redli在2002-11-16 16:16:00的发言：
2) For some birds the sense of smell appears to play a role in navigation, since pigeons with surgically removed olfactory nerves were found to have increased difficulties in homing.

QUOTE:

(B) have been found to have increased difficulty.

(E) have been found to have increasing difficulties

请教：为什么(E)选项错误？

redli

第二题，
1）觉得过去时也没什么错，即“已经被发现”，因其前面跟了个结论“For some birds the sense of smell appears to play a role in navigation”
2）除了时态，difficulty在单复数上有什么区别？

猫猫头

1、抽象名词优于从句
2、前面是现在时呀，而且句子中并没有明确的点提示你这是发生在过去