You should always keep to the speed limit.

什么时候你都不得超过最高速度限制。

《牛津词典》

You've got to keep to the speed limit.

你必须遵守限速的规定。

《柯林斯英汉双解大词典》

A lot of people are in a rush, and it's very difficult to keep careful, for they would rather care for their speed than your safety.

很多人都在赶时间，很难保持小心谨慎，因为他们更关心自己的速度，而不是你的安全。

youdao

Remember, you've got to keep track of the sign of acceleration, so if you're picking up speed towards the ground, a is negative, so it will be g plus a, but a is a negative number.

记住,一定要注意加速度的符号,所以当你加速下降的时候,a 是负的,还是 g 加上 a,但是 a 是负数

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