Instruction: Output yes if the supporting document can answer the given question. Otherwise, output no.

Input:
Question: what is the supply voltage ? can it work under 220 V 50 Hz
Document: I normally do not write reviews, but this product just made me come here to recommend it.I'm incredibly impressed by the INCREDIBLE light it delivers, at night you can work at your desk pretty much as if you were working by day. It is really flexible, it has five levels of intensity, as well as four modes which are indeed pretty good at delivering varied tones of light. It is totally worth it, buy it with confidence!
I can work at my computer, pay bills, and do other desk work without having the overhead light on in the room. This lamp casts a pleasing and bright-enough light to be used day or night.If this lamp had a longer arm, and the ability to swivel back and forth as well as up and down, it would get five stars from me. Still, for my purposes, it's the best I found and I'm pleased with the purchase.
But then again, my boyfriend has taken naps in my room while I work, so maybe it'll benefit him.- Also, the angle or height may be a little limited compared to some other desk lamps, but who needs desk lamps that shine onto the ceiling or from 3 feet above the desk or 3 inches from the desk?Overall:The price may be a little hefty, but I think it's a great investment, and you get what you paid for.
I recently purchase the Softech-Natural Light LED Multi-function desk lamp. I was hesitant about the purchase because I had not been able to actually see and test the lamp before purchase. I have to say I am very, very pleased with it and do recommend it to others.It stands at a good height so it casts a soft light over my work area. The light is not harsh and does not give me eye strain and headaches as my last lamp did.
I love this lamp. I have one at work and one at home. I love the light spectrum it provides, and so far solid operation. I have not had any issues, and when I press the hour timer around 5 PM it turns off every time in 1 hour. Reliable high quality product.I have also noticed that when I use the focus light spectrum, that I do get more work done, and have reduced eye fatigue.
[NOT made in China, by the way ... Made in Korea. ][Sept 18, 2012, supplemental remark:  I bought two more of these; one as a gift and one for a side table near my computer][November 23, 2013, supplemental remark:  I bought two more; one because one of our rooms is very dark due to the way the bookshelves are placed.
[Be aware, though, that the plug comes in two pieces, mysteriously  --  I spent a bit of time trying to figure out how to make the prongs come out the regulation distance, before I realized that there was one more little piece taped into the carton. Once the light dawned, another two seconds. ]The body of the light is gorgeous in its simplicity  --  it's made of that good, dense, sleek, Italian-looking plastic, and so slender!
Would buy again or purchase a second one if it were needed elsewhere.
Works well, my 5 year old loves playing with the multple setting. Actually encourages her to sit at her desk and do her homework!
With adjustable color temperature and light output, it's a very versatile, and stylish, light. I ordered a pair, and use them to illuminate a fly-tying desk. I've even used them to light some items on a copy stand that were destined for Craigslist and Ebay, and the daylight color temperature setting makes lighting a breeze. Because the light isn't hooded like an architect's syle lamp, there is some glare if the LEDs are slightly above your eye level, but that's easily adjusted.
Answer: no