请观察,下面标1,2的短句是如何结合成长句的.
1.There is a boy.
2.The boy is running around the field.
-There is a boy running around the field.
1.I can see a boy.
2.The boy is running around the field.
-I can see a boy running around the field.
1.Who is the boy?
2.The boy is running around the field.
-Who is the boy running around the field?
1.Who is the weary lady?
2.The lady is standing at the rear.
-Who is the weary lady standing at the rear?
这是个简单句,lady 之后需要的是修饰限制性的成分：定语.能做定语的,结构有：
介词短语、分词短语、定语从句、形容词、动词不定式等.
-Who is the weary lady standing at the rear?中,standing 是现在分词,非谓语形式,合适.
lady 之后不能用动词的谓语动词形式,stands,stood,is standing,stood,has stood,等任何谓语动词结构都不可以.因为,在一个简单句中,只能有一个主语,一个谓语.
此情形下,要想使用一个动词的谓语形式,必须在一个从句中使用,即：
Who is the weary lady that is standing at the rear?
Who was the weary lady that stood at the rear?
对于许多英语学习者来说,经常遇到这个问题,或者说在此处反复弄错,很难改正（一旦成习惯,没什么好办法改）.鉴于,您还不知道stand 的过去式是stood,暂时先保留诸多为什么的疑问,只要先记住：
Who is the weary lady (standing) at the rear?中,括号中v+ing形式是正确的,即可.等所有语言现象都学到了后在解决其他疑问.