I guess the usage of "be" in the passage below is grammatically correct even though the whole narration is in the past tense. Can you, please, explain to me why it is correct and why it is not "was" instead?
I liked working at the lab and doing all those experiments with acids and alkalines. At first, my interest was so great that I simply ignored Jack's suggestion to use that device. However, the more I continued, the more I was upset about spilling acid on the floor almost every time I experimented on it. One day - almost by accident - I showed up in the nearby lab where the parallel class students were experimenting. What struck me a lot was the fact that they never spilled any liquids that they were "playing with" - not only acids. Another thing that also struck me a lot was that they all were using exactly that device that Jack had suggested that I would do a few days earlier. I quickly went back to my lab and started studying that device. It took me a while to figure out how to use it. Finally, I realized that that was quite a handy device that I could always use in my experiments and never be afraid of spilling acid on the floor again.