There are about five

A
试题分析:
句意：山上有大约五百棵小树。hundred百，hundreds
of成百上千我；前加具体数字时，hundred不加s，故选A.

扩展阅读：only a little more than ... are you ok ... i am doing my homework ... there are a great many ... sounds like fun ... you got me feeling blue ... there is some milk ... there are no books ... there is a girl ...