beforehand/ahead.导航词义：事先，提前

1. beforehand:adv. 事先，预先，事前.指在时间上先于另一事发生或完成，尤用于谈论准备或计划的事情。

If you have completed most of the homework beforehand, you'll enjoy the evening more.

如果你预先把大部分家庭作业做完了，这个晚上你会玩得更开心。

Please inform us of your arrival time beforehand.

请事先通知我们你抵达的时间。

Saunas can be dangerous if misused. Avoid a big meal beforehand.

洗桑拿浴如果方法不当会有危险，浴前切忌饱食。

How could you tell beforehand that I was going to buy a Ford?

你怎么会事先知道我要买一辆福特轿车？

2. ahead:adv. 事前，提前.词义同 beforehand，常可换用；但以 ahead of time/schedule 出现时，则其中的 ahead 不可与 beforehand 换用。

Do book ahead/beforehand as the hotel is very popular.

该酒店非常受欢迎，请务必提前预订。

Winter weddings need to be arranged months ahead/beforehand.

在冬季举行婚礼需要提前几个月作安排。

If you had warned me ahead of time, I wouldn't have done that.

如果你预先警告我，我就不会那样做了。

The train left 3 minutes ahead of schedule.

火车提前3分钟离站了。

全部

1·I wish we'd known about it beforehand.

要是我们预先知道这事就好了。《牛津词典》

2·I have to say in her defence that she knew nothing about it beforehand.

我得为她说句话，她事先并不知道此事。《牛津词典》

3·It is reasonable to assume that he knew beforehand that this would happen.

有理由认为他事先就知道会发生这样的事。《牛津词典》

4·She is always beforehand with the rent.

她总是预先付房租。《新英汉大辞典》

5·You must have some preparation beforehand.

你必须事先做些准备。

6·Strategies to be used in each can be planned beforehand.

每一种要使用的策略都可以事先规划好。

7·As a further precaution, all the crows had been fed beforehand.

作为进一步的预防措施，所有的乌鸦都预先喂过食。

8·These stages can be studied, and strategies to be used in each can be planned beforehand.

可以研究下这些阶段，也可以提前设计每个阶段所用的策略。

9·Were these stories really passed down through the generations or did you contact people and prep them beforehand?

这些故事真的是代代相传的吗，还是你与他们联系，请他们事先准备的呢？

10·Before using social media to screen job candidates, consulting with management and legal teams beforehand is essential in order to comply with all laws.

为了遵守各项法律，在使用社交媒体审查求职者之前，应该事先咨询管理层和法律团队，这是至关重要的。

事先

1·I have to say in her defence that she knew nothing about it beforehand.

我得为她说句话，她事先并不知道此事。《牛津词典》

2·It is reasonable to assume that he knew beforehand that this would happen.

有理由认为他事先就知道会发生这样的事。《牛津词典》

3·Were these stories really passed down through the generations or did you contact people and prep them beforehand?

这些故事真的是代代相传的吗，还是你与他们联系，请他们事先准备的呢？

4·Before using social media to screen job candidates, consulting with management and legal teams beforehand is essential in order to comply with all laws.

为了遵守各项法律，在使用社交媒体审查求职者之前，应该事先咨询管理层和法律团队，这是至关重要的。

5·It worked out well, by making my first move, but there was a lot of groundwork to be put down beforehand that helped me make that move a little bit easier.

我首先迈出第一步很有效，但是事先，我得打下许多基础，以帮助我迈出那一步稍微容易一些。

预先

1·I wish we'd known about it beforehand.

要是我们预先知道这事就好了。《牛津词典》

2·She is always beforehand with the rent.

她总是预先付房租。《新英汉大辞典》

3·As a further precaution, all the crows had been fed beforehand.

作为进一步的预防措施，所有的乌鸦都预先喂过食。

4·Provide participants with questions and clear definitions beforehand.

为参与者预先提供问题和清晰的定义。

5·This example also works in cases where you know the structure of the XML data beforehand.

这个示例在您预先知道XML数据结构的情况下也能够正常运行。

事前

1·Had parents been training their children beforehand?

是不是父母事前训练过孩子？

2·To be wise is to think of everything beforehand.

聪明的人就是事前考虑一切事情。

3·Simple summary of the post is useless, the key is to anticipate certain laws beforehand.

简单的事后总结都是无用的，关键是事前能够预期的某些规律。

4·The biggest part in communicating effectively is preparing what you want to say beforehand. Keep it simple. What's my point? Why? Prepare a good example.

有效沟通最关键的是在于事前准备你想要说的是什么，这得简单明了，我的重点是什么，并准备一个好的例子。

5·Susan knew that Cory was coming because he had phoned her beforehand.

苏珊知道柯瑞会来，因为他事前打了电话给她。

预

1·In the path tracking module, adopt the beforehand aiming arithmetic based on PID controller, including the speed control and turning control.

在路径跟踪模块中，采用了基于PID控制器的预瞄控制算法，包括速度控制和转向控制。

2·The results indicate that maths-model can beforehand shield performance of ir smoke, and some of results are confirmed by experiment, the experiment results are according with simulated results.

结果表明，本文建立的质量消光系数计算数学模型可用于预估红外烟幕遮蔽性能，而且模拟结果与实验结果基本吻合。

3·The Interpretation of Remote sensing image Indoor beforehand can greatly increase the production efficiency of Present land use map based on Remote sensing image.

利用遥感影像制作土地利用现状图时，在室内先对影像进行预判解译，可以提高土地利用现状图制作的工作效率。

4·Stress and beforehand close quantum of helix torsion spring of rectangle section is educed by some conclusions of mechanics of materials and compute formula.

该弹簧是保证调整臂正常工作的关键件，本文从材料力学的结论出发，详尽地推导了该弹簧应力及其初始预紧量的设置，并给出它们的计算公式。

5·We parse the XML files beforehand to create indexes of content, and then search the indexes. 4.

检索过程中首先对XML描述文件进行预解析，建立动态的内容索引，然后对索引进行检索。

先行

1·In this paper, the fuel gas and propellent system of in site Pellet injector used in beforehand experiment and Pellet fueling experiment in HL-1 Tokamak has been introduced.

本文介绍了“原位冷凝”式弹丸注入器先行实验及中国环流器一号HL-1弹丸加料实验中采用的丸料气和推进剂系统；

2·Where it is necessary and it is possible, it may file an application beforehand or concurrently at the country or region where the importer is located.

确有需要并条件具备的，可先行或同时向进口方所在国家和地区提交专利申请。

3·Tai Zhong said: Are the orthodox and unorthodox distinguished beforehand or are they determined at the time of battle?

太宗问：奇兵与正兵是平时就先行区分的，还是临时根据情况而决定的呢？

在此之前

1·Beforehand, the students have been carefully prepared for the language learning experience.

在此之前，学生们已经做好了学习语言的准备。

2·Beforehand, some members of the trial were allowed to view the Facebook profile of the person they were trying to win over.

在此之前，这项实验的一些成员被允许查看他们试图去赢得支持的人员的 Facebook 资料。