The retired man donated most of his savings to the school damaged by the earthquake in Yushu ,________the students to re

The retired man donated most of his savings to the school damaged by the earthquake in Yushu ,________the students to return to their classrooms.
A.enabling B.having enabled
C.to enable D.to have enabled
Schools across China are expected to hire 50,000 college graduates this year as short-term teachers,almost three times the number hired last year,__________ reduce unemployment pressures.
A.help B.to have helped C.to help D.having helped
第一题正确答案选A,现在分词做结果状语,不能选不定式,是因为不定式做目的状语要放在句首,或者放在句中和句末不加逗号
第二题正确答案选C,不定式做目的状语,怎么前面有逗号?
而且不是help to do么?
如果第二题可以选C,那么第一题为什么不能选to enable做目的状语?
两道都是江苏高考题