1. letter
2. mail
3. to trust
4. to believe
5. to profess faith in
6. truthful
7. confidence
8. trust
9. at will
10. at random

classifier: 封

1. to use; to make use of; to employ
2. (coverb) with; using
3. to need; to have to (usu. used in the negative or in questions)
4. usefulness; utility
5. (bound form) expense; outlay
6. (courteous) to eat; to drink
7. (literary) hence; therefore