enter on/upon

(formal)begin (an activity or job); start to pursue (a particular course in life)

(正式)着手（活动，工作）；开始（生活道路）

he entered upon a turbulent political career.

他开始了动荡不定的政治生涯。

(Law)(as a legal entitlement) go freely into (property) as or as if the owner

(律)（作为法律赋予的权利）正式占有

enter into

To participate in; take an active role or interest in

加入：参加；在其中扮演一个积极的角色或对其有兴趣

enter into politics; enter into negotiations.

从政；参加谈判

To become party to (a contract)

缔结：成为（一项条约）的订立方

The nations entered into a new agreement.

这些国家签署了一项新的协议

To become a component of; form a part of

使纳入：是…的一部分；构成…的一部分

Financial matters entered into the discussion.

财政问题纳入讨论之列

To consider; investigate

考虑；审议

The report entered into the effect of high interest rates on the market.

这报告讨论的是市场高利率的影响

enter on 或 enter upon

To set out on; begin

着手；开始

We enter on a new era in our history. They entered upon the most dangerous part of the journey.

我们进入了历史上的新纪元。他们开始了旅行中最危险的阶段

To begin considering; take up

开始考虑；着手做

After discussing the budget deficit, they entered on the problem of raising taxes.

讨论过预算赤字之后，他们开始考虑增税问题了

To take possession of

占有，获得

She entered upon the estate of her uncle.

她获得了她叔父的不动产