下列各项哪个是外国直接投资，哪个不是？
a．一个沙特阿拉伯的商人购买了1000万美元的IBM公司股票。
b．上述商人又购买了一套位于纽约的公寓。
c．一家法国公司兼并了一家美国公司，原美国公司的股东把股票换成法国公司的股票。
d．一家意大利公司在俄罗斯建立了一家工厂，并作为俄罗斯政府的承包商来管理该工厂。
Which of the following are direct foreign investments，and which are not？
a．A Saudi businessman buys $10 million of IBM stock．
b．The same businessman buys a New York apartment building．
c．A French company merges with an American company：stockholders in the U.S. Company exchange their stock for shares in the French firm．
d．An Italian firm builds a plant in Russia and manages the plant as a contractor to the Russian government．