He was out of control. Throwing things, banging… banging his head… He opened the car door when I was doing seventy, nearly killed us both.

The speaker is his mother and he has a developmental disorder.

what does 'doing seventy' mean? She was driving at the speed of 70km/h?

Help me to understand it! (My native language is not English. Please be kind to me. :-))

  • 3
    Yes, it relates to the vehicle speed (in km/h or mph).
    – KillingTime
    Commented Oct 24, 2019 at 12:01
  • @KillingTime Thank you! Commented Oct 24, 2019 at 12:03
  • 5
    Please show evidence of research. [Lexico], for instance, has 'do 2.2 Travel at (a specified speed) ‘I was speeding, doing seventy-five’'. // An even more unexpected idiom is 'They were clocking ninety'. // You will probably find our sister site, ELL, more suitable for basic questions. Commented Oct 24, 2019 at 12:19
  • Hello Lily. I do not normally vote to migrate to ELL, but in your case I am going to start making an exception. Your questions are very basic for this site. Commented Oct 24, 2019 at 16:39

1 Answer 1


You are correct that the speaker is referring to speed. Depending on the locale, speed could either be measured in kilometers per hour or miles per hour. It looks like this quote is from the show Law & Order: Special Victims Unit. I haven't seen the episode, but if it takes place in the United States, the reference is to miles per hour.

Here's the relevant definition of "do" from the OED:

To traverse (a given distance); to achieve; to travel at (a certain speed, etc.).

You can use this context of the word to describe other travel-related activities. For example "I did 300 miles yesterday while doing 50" would mean you drove 300 miles at a speed of 50 miles per hour.


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