There are several ways to express uncertainty. "~ darou" is a plain form of "~ deshou," and means "will probably." The adverb "tabun (perhaps)" is sometimes added.
| Kare wa ashita kuru deshou. 彼は明日来るでしょう｡ | He will probably come tomorrow. |
| Ashita wa hareru darou. 明日は晴れるだろう｡ | It will be sunny tomorrow. |
| Kyou haha wa tabun uchi ni iru deshou. 今日母はたぶんうちにいるでしょう｡ | My mother will probably be home today. |
"~ darou" or "~deshou" is also used to form a tag question. In this case you usually can tell the meaning from the context.
| Tsukareta deshou. 疲れたでしょう｡ | You were tired, weren't you? |
| Kyou wa kyuuryoubi darou. 今日は給料日だろう｡ | Today is a payday, isn't it? |
"~ darou ka" or "~ deshou ka" is used when guessing with doubt. "~ kashira" is used only by females. A similar expression used by both genders is "~kana," though it is informal. These expressions are close to "I wonder ~" in English.
| Emi wa mou igirisu ni itta no darou ka. エミはもうイギリスに行ったのだろうか｡ | I wonder if Emi has already gone to England. |
| Kore ikura kashira. これいくらかしら｡ | I wonder how much this is. |
| Nobu wa itsu kuru no kana. のぶはいつ来るのかな｡ | I wonder when Nobu will come. |
"~ kamoshirenai" is used to express a sense of probability or doubt. It shows even more uncertainty than "~ darou" or "~ deshou". It is used when you don't know all the facts and are often just guessing. It is similar to the English expression "might be." The formal version of "~ kamoshirenai" is "kamoshiremasen".
| Ashita wa ame kamoshirenai. 明日は雨かもしれない｡ | It might rain tomorrow. |
| Kinyoubi desu kara, kondeiru kamoshiremasen. 金曜日ですから､ 混んでいるかもしれません｡ | Since it is Friday, it might be busy. |
* Compare these sentences.
| Kare wa tabun kin-medaru o toru deshou. 彼はたぶん金メダルを取るでしょう｡ | He will probably get the gold medal. |
| Kare wa kin-medal o totta no kana. 彼は金メダルを取ったのかな｡ | I wonder if he got the gold medal. |
| Kare wa kin-medaru o toru kamoshirenai. 彼は金メダルを取るかもしれない｡ | He might get the gold medal. |
The last thing to mention is, "~ darou" or "~ deshou" can't be used when referring to one's own actions, though "~ kamoshirenai" can be used in these situations.
| Ashita watashi wa Kobe ni iku kamoshirenai. 明日私は神戸に行くかもしれない｡ | I might go to Kobe tomorrow. |
| Ashita watashi wa Kobe ni iku darou. | Wrong |
| Ashita ane wa Kobe ni iku darou. 明日姉は神戸に行くだろう｡ | My sister will go to Kobe tomorrow. |
