we have a foolproof,no-cook frosting中的"frosting"为什么要加ing?

We have succeeded in finish the hard work 中的finish为什么要加ing We're going to have a drawing coneat today.为什么draw要加ing? we have a new family joining us today,这里的join为什么要加ing? no后面为什么要加ing? we are all having a good time中的hveing为什么加ing? have no regrets中的regret为什么要加s 请问have为什么要加ing? Was he cooking at six last night?为什么cook要加ing 帮我看看这个句子中的have为什么要加ING i have been teaching since 2006中的teach为什么要加ing? 为什么要有have a better 和 understanding 为何加ing We watched a movie about living on Mars.为什么要用living?加ing?