是这样的,be going to 用在你在说话之前就决定去做的事情上,而will do是当你在说话的时候做了决定才用.我不知道怎么用中文解释,给你个例子吧：
Helen:My bicycle's broken.Can you fix it for me?
Father:Okay,but I can’t do it now.I’ll fix it tomorrow.
父亲是在听完之后才决定的去修自行车,所有用的是will do.
反之：
Mother:Can you fix Helen’s bicycle?It's broken.
Father:Yes,I know.She told me.I’m going to fix it tomorrow.
父亲之前决定了明天去修,所以此时用的是be going to do.
所以这题应该是nobody will take them.