1 . The other day, ________ occurred to Johnson that he should make a road trip to help the needy. (用适当的词填空)

2 . You may rely on ________ that it won’t happen again. (用适当的词填空)

3 . I would appreciate ________ if you could keep silent. (用适当的词填空)

4 . ______ is acknowledged to us all that the old scientist, for whom life was hard in the past, still works hard in his eighties. (用适当的词填空)

5 . It is no use ________ (tell) him the witty words , because he never smiles. (所给词的适当形式填空）