I'm not sure whether I should tell you this.

　　我拿不準該不該把這事告訴你。

　　She asked her boss whether she could have the day off.

　　她問老板可不可以讓她請一天假。

　　You've got to go to school, whether you like it or not.

　　不管你喜歡不喜歡，你得上學。

　　It's doubtful whether the car will last another year.

　　這輛汽車未必還能用上一年。

　　It remains to be seen whether his project will fly.

　　他的計劃能否成功尚需拭目以待。