The third popular Chinese character master series
“Idiomatic Master Elementary School Level 200” iPad version released!
https://itunes.apple.com/jp/app/guan-yong-jumasuta-xiao-xue/id807324630?mt=8

“Formula Master” is a practice app that contains 200 words of formulas that are useful to know.
Formulaic language is a set of words, phrases, or phrases that have been widely used as a habit for a long time. A compound word in which two or more words are tightly connected and have completely different meanings, and they are used as fixed phrases in conversations and sentences.