其中一大挑戰是

其中 qiˊ zhongˉ

(Among, From among, Within) Within, Among, From among

一大挑戰 yiˊ daˋ tiaoˉ zhanˋ

(big challenge) A big challenge

挑戰 tiaoˉ zhanˋ

(Challenge, Challenged, Challenges, Challenging, To challenge) Challenge, Challenges, A challenge, The challenge, The challenges, To challenge, Challenging, Challenged

是 shiˋ

Is, To be, Am/Are/Is/Was/Were, Being, Yes