the expectation is that ..., the reason is that ..., the fact is that ..., the explanation is that ..., it is that ...
Verb or い-Adjective +
This formation is used with verbs and い-adjectives to provide an explanation, emphasize a reason, or ask for clarification based on the current situation.
Verb (Informal Form)
The informal form of the verb (present or past) is followed directly by
図書館に行く
The fact is that I am going to the library.
食べすぎた
It is because I ate too much.
い-Adjective
The informal form of an い-adjective (present or past) is followed directly by
寒い
The reason is that it is cold.
高かった
It's because it was expensive.
な-Adjective or Noun + な +
When using な-adjectives or nouns in the present tense, the particle な must be placed between the word and
な-Adjective
Add な to the stem of the な-adjective before adding
静かな
The fact is that it is quiet.
好きな
It's because I like it.
Noun
Add な to the noun before adding
学生な
The explanation is that I am a student.
休みな
It's because it is a holiday.
For the past tense of nouns and な-adjectives, use だった