問題

もんだい

problem, question, issue

問題ない

もんだいない

no problem, no issue

話題

わだい

topic, subject of conversation

課題

かだい

task, assignment, challenge

宿題

しゅくだい

homework

本題

ほんだい

main subject, main topic

時間の問題

じかんのもんだい

matter of time, question of time

放題

ほうだい

as much as one likes, unlimited

話題になる

わだいになる

to become a topic of conversation, to become talked about

本題に入る

ほんだいにはいる

to get to the main point, to get down to business