How to pronounce 挺直 in Cantonese (2 out of 3):

保持背挺直 別彎腰
Keep your back straight, and don't lean.

Cantonese Sentence Breakdown

保持 bou2 ci4
maintain
bui6
to learn by heart
to recite from memory
unlucky (slang)
hard of hearing
out of date
unfashionable
ignorant
remote
挺直 ting2 zik6
straighten up
bit6
to leave
to depart
to separate
to distinguish
to classify
other
another
do not
must not
to pin
to stick (sth) in
distinction
category
alternative
special
彎腰 waan1 jiu1
bend over