莹火虫妹妹
前者。因为如果用there is a tree is standing ，那么句子里有两个谓语了，分别是there is 以及is standing ，但是在一个英语的句子里，是不允许这样的（并列谓语除外），所以第二个亦不能理解做现在进行时。这也是为什么有谓语动词和非谓语动词之分的原因之所在。第一个句是there be 结构，加上现在分词做伴随状语的结构。类似的句子：1.There are several boys playing football.2.There was a girl sitting on the chair.掌握要诀才是关键！！！
飞扬嗒兜兜
房子前面有一棵树用英语There is a tree in front of the house
双语例句：
1、房子前面有一棵树，树下拴着一头母牛。
Before the house stands a tree, under which a cow is tied.
2、我们家房子前面有一棵4米高的树。
There is a4-metre-tall tree in front of our house.
3、在房屋前面有一棵树。
There is a tree in front of the house.
4、她的房间外面有一棵树。
There was a tree outside her room.
5、房前有一棵很高的树。
There was a tall tree in front of the house.
6、那座房子前有一棵树。
There is a tree in front of that house.
