what is dog doing 還是what is a dog doing,那個對 還有is dog running

題目：

what is dog doing 還是what is a dog doing,那個對 還有is dog running across the street,還是is a dog,這兩個句子到底用不用冠詞a 啥時候用冠詞各位大仙求解

解答：

如果是不特指的東西,單數就用a/an.比如,I have a pen
如果所指的物品有獨特的屬性或者特指某一個,就用定冠詞the
如,A dog is a house-keeper.
The dog is a good house-keeper 再答： 所以你上面的句子裡dog都是特指的過馬路或者做什麼的那隻狗，應該用the
再問： 特指明白了，