I'm very confused about these two grammar points. The 新完全マスターN2 book doesn't explain about the type of verbs which may precede these two points, and I don't understand why some of the answers in the book are the right or wrong.
Some sources online say that only Sino-Japanese verbs or honorific language may be used with them, yet an example in the book says 発音を調べる際に… If this is okay, then I don't know why for one of the questions お食事の際は…is correct but ご飯を食べる際は… is unacceptable.
Can someone please explain any restrictions in usage. I understand that it is official language and not used in everyday speech, but is it true that only Sino-Japanese verbs can be used?