有一读者问： 有这样一道选择题：
Few people realize that Siberia is extremely rich in natural resources,_________oil and gas but also vast resources of coal, timber, land and water.
A. not only B. has
C. has not only D. having not only
答案为D，固然无可非议，但我认为答案A也不错。因为A与其后的一连串名词可用作其前的resources的同位语，不知对否？
应选D。A之所以不妥是因为同位语一般不用not only...but also...。
