Limb是“肢”或者“枝”，这个短语是什么意思呢？请看对话：

    A: We still need someone to help decorate the venue for Saturday’s party. Can you give a hand?

    B: I’ve already gone out on a limb. I’ve designed the invitation and will do the food and drinks shopping. I’ve got a full-time job too, so there is nothing more I can do.

    Note: The idiom means to “put oneself in a tough position in order to support someone or something.” The clear allusion in this phrase is to climbing trees. All of us must remember that feeling of not wanting to go further out to reach that apple or whatever for fear that the branch (limb) would break under us. The first use of it in a figurative sense, with no reference to actual trees or climbing, comes from the United States at the end of the 19th century.