～際に　and ～に際して grammar


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?




～際【さい】 is only a more formal (business-like) variant of ～時 and ～折【おり】, thus 「A
際（に／は）B」 just means "B when A" or "B on the occasion of A".

On the contrary, 「A に際して B」 is more like "B taking A as an oppotunity",
synonymous with ～にあたり. Compared to 際:

  * _A_ isn't necessary to be exact when _B_ happens

> 初めてのご利用 **の際に** ご注意申し上げます。 (I'll warn you when you start to use)  
>  初めてのご利用 **に際して** ご注意申し上げます。 (Maybe you don't use right now but I warn you
> now)
>
> 来年アニメ100周年を迎える **際に** 展示を行う。 (the exhibit is in next year)  
>  来年アニメ100周年を迎える **に際して** 展示を行う。 (the exhibit can be this year)

  * _B_ is something special, intended action 

> ○ 帰国の **際に** パスポートを失くした。  
>  × 帰国 **に際して** パスポートを失くした。

  * _A_ should not happen before _B_ , never takes past form

> ○ アメリカに行った **際に**  
>  × アメリカに行った **に際して**
>
> × 昨年の地震 **に際して** 慰霊式を執り行った。

As for お食事の際は and ご飯を食べる際は, I don't know what exactly they say, but generally
they have different meanings that sometimes not interchangeable, irrelevant to
際. 食事 is for "having meal" and ご飯を食べる refers to the act of "eating food".

> _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?_

No. Although we prefer same word origin rule when building compound nouns
(一組【ひとくみ】 vs 一式【いっしき】 vs ワンセット), but it's rather for the sake of euphony.
Japanese doesn't have agreement on etymology among separate words, though it's
true that Sino-Japanese words are often more formal than native words, and you
should pick formal words throughout formal style of speech.

