垫底儿
diàn​dǐ​r

to put at the bottom

垫底儿 墊底兒 diàn//dǐ​r
to put at the bottom
to place something at the bottom or underneath something else
to have a snack
to have a small bite to eat to tide oneself over until a full meal
to be at the bottom
to come last in a ranking or competition; to be the lowest
to take responsibility
to take responsibility for something; to bear the burden
to lay the foundation
to do spadework or lay a foundation for further development