1. join in: to start taking part in something that other people are already doing, especially something enjoyable such as a game, or a song

例：

James joined in the discussion to say that he agreed with what had been said. （詹姆斯参与了讨论，他说他同意之前的讨论结果。）

He stared at them without joining in the conversation. （他看着他们，没有插嘴。）

He laughed loudly, and Mark joined in. （他大笑，然后马克也跟着大笑起来。）

join in something

In the evening there was a barbecue, with the whole village joining in the fun. （晚上有烧烤活动，全村同乐。）

join in with

As a child, I was too shy to join in with the other children's games. （我小时候，太害羞了，都不敢跟其他小朋友一起玩。）

2. get involved: to start to take part in something, often something that will cause you problems or take a lot of your time 卷入

例：

It's a private matter between the two of them, and I don't think we should get involved. （这是他俩的秘密，我觉得我们不要搅进去。）

get involved in

When did Anderson first get involved in local politics? （安德森什么时候开始参与地方事务？）

I don't want to get involved in an argument with you on the phone. （我不想在电话里跟你吵。）

The US seemed unwilling to get involved in another war. （美国好像不愿意再卷入另一场战争。）

3. get in on the act: to start to take part in something that is already successful, especially a new type of business that other companies are already involved in 分一杯羹

备注：''get in on the act''常用于非正式的场合。

例：

Now that our exporting business to Eastern Europe has grown so successful, everyone wants to get in on the act. （我们出口东欧的项目做得很好，大家都想来分一杯羹。）

4. jump the bandwagon: to start to take part in an activity because a lot of other people are doing it and not necessarily because you believe in it 蜂拥而至

备注：也可写作''climb/get on the bandwagon''。

例：

When they realized there was money to be made from games such as snooker, sportswear advertisers soon jumped on the bandwagon. （一发现像斯诺克之类的运动很赚钱，运动服广告商便蜂拥而至。）

5. muscle in on: to deliberately interfere in a plan, activity etc. that other people are organizing so that you can have some of the advantages of that situation 插手

备注：''muscle in on''常用于非正式的场合。

例：

I'm not going to let Jim muscle in on this deal - let him do his own negotiations. （我不会让吉姆插手这宗交易，让他把自己手上的谈判谈好。）

6. get/enter into the spirit: to relax and take part in a party, celebration, or special occasion and to start feeling happy, or excited as the people around you 融入氛围

例：

This year Pat decided to get into the spirit and decorate her house for Halloween. （今年万圣节，派特决定要融入到节日气氛中，好好装饰一下自己的屋子。）

Although Mark felt depressed he did his best to enter into the spirit for Julie's sake. （尽管马克情绪沮丧，但为了朱莉，他还是尽量融入这个氛围。）

get/enter into the spirit of

You'll enjoy yourself much more if you just relax and try to get into the spirit of the occasion. （如果你放松心情，融入其中，你会玩得更开心。）