Example 1
彼が来るかどうか知りません。
Kare ga kuru ka dou ka shirimasen.
I don't know if he will come or not.
Breakdown
tokenkare (he) - kuru (come) - ka dou ka (whether) - shirimasen (don't know)
Example 2
この本が面白いかどうか教えてください。
Kono hon ga omoshiroi ka dou ka oshiete kudasai.
Please tell me if this book is interesting or not.
Breakdown
tokenkono (this) - hon (book) - omoshiro(i) (interesting) - ka dou ka (whether) - oshiete kudasai (please tell)
Example 3
彼女が綺麗だかどうかは分かりません。
Kanojo ga kirei da ka dou ka wa wakarimasen.
I don't know whether she is beautiful or not.
Breakdown
tokenkanojo (she) - kirei (beautiful) - da ka dou ka (whether) - wakarimasen (don't know)
Example 4
彼が先生だかどうか覚えていません。
Kare ga sensei da ka dou ka oboete imasen.
I don't remember if he is a teacher or not.
Breakdown
tokenkare (he) - sensei (teacher) - da ka dou ka (whether) - oboete imasen (don't remember)