had being的用法和樣例：
例句
- He postulated that a cure for the disease will have been found by the year 2000.
他推斷到2000年能研究出治愈該病的方法。 - Our partnership dates back to (ie We have been partners since) 1960.
我們從1960年就合伙了。 - I had been a footman for 20 years.
我曾做過(guò)20年的聽(tīng)差。 - I have been instructed by my agent that you still owe me 100 pounds.
我的代理人通知我，你還欠我100磅。
