(1)投資(investing of money)[U，N(in)]：capital～資本投資;～in real estate/enterprise/oil stocks 房地產(chǎn)/企業(yè)/石油股票投資;a promising field for～有前途的投資領域;By careful/wise～，he obtained a big profit. 他靠精心/明智的投資而獲巨額利潤。
(2)投資額(amount of money used for the act of investing)[C，N(in)]：make an～of $100，000 in a project 在一工程上投資10萬美元;a good/poor/lucrative/risky/safe and sure/sound～值得/不當/有利/冒險/安全可靠/穩(wěn)妥的投資;heavy/huge/long-term/overseas～s 巨額/巨額/長期/海外投資;～bank/company 投資銀行/公司;
(3)(可)投入資金或時間的事物(sth on which money or time has been spent in the hope of future advantage or profit)[C]：Real estate/A new tractor is a good～. 房地產(chǎn)/一臺新拖拉機是一項很好的投資。It might be a better～of time to teach children to cook. 教孩子做飯可能是一種較好的時間投入。