不可撤销资产：看第二段最后一句话“for the irrevocable trust, the cost basis of investments does not change, and the assets are not subject to estate taxes” 即不可撤销信托的税基不变，并且没有遗产税，所以仅仅需要在T时刻（将来）卖掉资产中股票变现的时候，交capital gain tax，所以不可撤销信托将来被征得税是：[2million*(1+r)^t-200,000]*20%
