It's difficult ______ the old people ___
问题:
It's difficult ______ the old people ______ walk up the Great Wall. [ ]
A. for, for
B. to, to
C. for, to
D. to, for
It's difficult ______ the old people ______ walk up the Great Wall. [ ]
A. for, for
B. to, to
C. for, to
D. to, for