Though people of two countries cannot go across the border without permission, animals, however, can cross the border freely.

虽然两国人民未经许可不能越过边境，但动物可以自由跨过边境。

youdao

When people cross the street, they flash to "tell" drivers to slow down and wait for people to go across the street.

人们过马路时，它们会闪灯“告诉”司机减速，等待人们过马路。

youdao

Don't cross (go across) the street without looking around.

横过马路前要先左右看。

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and Mexican officials. Every day, thousands of people on foot and in vehicles go back and forth across the border here, and millions of dollars worth of products cross the line in trucks and railroad cars.

VOA: standard.2009.04.30

Ultimately, the technology could go either way, acting as an effective method of cross-checking people across a vast security network as they move from country to country, or evolving into an omnipresent grid of surveillance that will spread viruses and confine us all to our homes lest we feel the wrath of cyber criminals or high-tech fascists.

ENGADGET: RFID Passports coming to the US in August