Americans like myself tend not to use "whether", but we use "if", for the most part. 'Whether' always introduces a choice, usually between 2 possible answers (or more alternatives, as romulus wrote). "I don't know whether or not I will go to the conference". (ich weiß nicht ob ich zum konference fahren werde) "Will he go to the party? I don't know whether he will (or not)" (ich weiß nicht ob er wird) I'm not sure about the British, Aussies or other speakers of English, but Americans tend to use 'if" in both of the above sentences, like so: "I don't know if I will go to the party" "Will he go to the party? I don't know if he will go to the party" This is why the German use of "ob" and "wenn" is hard for German beginners like me. 'If' tends to be followed by the (sometimes unspoken and unwritten) word 'then'. "If you invite me, (then) I will come to the party" (wenn du mich einladen, dann komme ich ... " In the above, you would never substitute "whether" And, of course, "Weather" ist Das Wetter. Sorry for my bad german translations! Brian

1. whether引导的从句常可以与连词or或or not直接连用，而if一般不能。如： 正(right)： Let me know whether you can come or not. 误(wrong)： Let me know if you can come or not. 2. 当宾语从句提到句首时，只能用whether引导，而不能用if。如： 正(right) Whether it is true or not, I can’t tell. 误：(wrong) If it is true or not, I can’t tell. 3. whether可以引导带to的不定式，if则不能。如： 正(right)I don’t know whether to accept or refuse. 误：(wrong) I don’t know if to accept or refuse. 4. whether及其引导的成分可放于介词之后，作介词的宾语，但if不能。如： 正(right)： I worry about whether I hurt her feelings. 误：(wrong) I worry about if I hurt her feelings. 5. whether可以引导从句，作主语、表语或同位语，而if不能。如： 正(right) It was uncertain whether he would come. 误：(wrong) It was uncertain if he would come. 正(right)：His first question was whether Tom had arrived yet. 误：(wrong) His first question was if Tom had arrived yet. 正：(right) We must consider the question whether we will take these measures. 误：(wrong) We must consider the question if we will take these measures.

"if" introduces conditional clause: "I'm going to your party if the rain stops." (on a condition that the rain stops, I will go to your party) "whether" introduces two (or more) alternatives: "I'm going to your party whether it rains or not." (in spite of the weather, I will go to your party.) "Let me know whether you will be there." here, the asker expresses an indirect question "will you be there (or not)?" "Let me know if you will be there." the conjunction "if" here may mean, "supposing that".... "supposing that you will be there, let me know." (I stand corrected on this). :)

Hello,DerVater Do you mean whether?