だろうか
(Daro u ka)
Used to express doubt, uncertainty, or to wonder about something.
Connection rules
- +Verb (Dictionary/Noun/Adj) + だろうか
Examples
1.
この計画で本当にうまくいくのだろうか。

Kono keikaku de hontouni umaku iku no daro u ka.
I wonder if things will really go well with this plan.
「Uncertain business meeting.」
2.
彼は今日、約束の時間に来てくれるだろうか。

Kare ha kyou, yakusoku no jikan ni ki te kureru daro u ka.
I wonder if he will come at the appointed time today.
「Waiting for a friend.」
Practice
The train is late; I wonder if I will make it in time for the meeting.
電車が遅れているけれど、会議に___。
Romaji also accepted