1) We use them every day and don't even think about them ( NOT THINK) - вся фраза в Present Simple
2) The U.S. no longer tests nuclear weapons. - нужно наречие
There is not enough money to support making nuclear wepone (LONG)
3) They need to be watched over to keep them absolutely safe (ABSOLUTE - по структуре предложения нужно наречие
4) The inventor who made the bomds still have a lot (INVENT) требуется существительное, если есть определяемое слово КТО, значит, это человек
5) of their research information. - требуется существительное потому что есть притяжательное местоимение their They did not want to get rid of it. (INFORM)
6) The nation`s nuclear weapons labs are trying to save that knowledge. - требуется существительное By having so many large bombs, the countries ... (KNOW)