Light up means to fill something with light or to become bright: The city lights up at night. The second meaning is to suddenly look very happy: Her face lit up. People say it about someone's face and eyes when they suddenly feel happy. The past form is lit up.
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something lights up; light up + room/sky/street; somebody's face/eyes light up (with + feeling); past: lit up
- In December the main square lights up with thousands of tiny lamps.
- His eyes lit up when the waiter brought the chocolate cake.
- The fireworks lit up the whole sky above the river.
What changed
First versionIt's getting dark, can you light up the lamp?
RevisionIt's getting dark, can you turn on the lamp?
Light up can look like the verb for a lamp, but lamps and lights are turned on or switched on: turn on the lamp. Light up describes something filling with light, not someone pressing a switch.
Light up has one more common meaning: to light a cigarette. He went outside to light up. The situation usually makes it clear: if someone steps out onto the balcony to light up, it's about a cigarette, not fairy lights.
Your turn
At night the whole bridge ___ in blue and gold, and tourists stop to take photos.
Show the answer
lights up — The bridge itself fills with light and shines: lights up. Switches on is used about a lamp or a device that someone turns on, not a bridge glowing with lights.
Describe a moment when someone was really happy. Say who it was and what made them happy.
My grandmother's face lit up when I told her I had passed my driving test.
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