Can two people working together lift a weight heavier than the sum of what each could lift on their own?

Yes, it's possible but it all depends on the leverage and grip they are able to get on the item as well as each person's individual strength.

Another tool that can help two people carry extremely heavy weights is the forearm forklift.

Not sure about the world record, I just know this from experience working as a removalist when I was younger.
What will happen if I do 80 sit-ups for 30 days?

Frankly speaking it depends on what you are doing with it:Fitness goal------- diet + workout + restIf you keep everything on the point then only you can expect results. But being a fitness trainer I would advice you to do planks instead of crunches. Because plank is the single exercise which

After going to boarding school, my 12-year daughter is changed completely. Whenever she comes to home in holidays, she stays in her room only and never comes out. She eats in her room, watches movies in her room. What should I do?

Your Daughter is undoubtedly depressed. You sent her away to a boarding school, at a time in her life when she may well be going through a lot of physical and emotional changes (girls start puberty far younger than you may expect these days). Then you expect her

What is the protocol for American astronauts at the International Space Station if a war breaks out with Russia?

On the ground, the United States and Russia might have conflicting interests, but in space, 250 miles above Earth, they get along nicely, mostly. There was some tension after the discovery of the leak in the Soyuz escape vehicle, but that played out in the media of both