hypothetically: 假设，假如（看完这段别再说不会用hypothetically了）

how come+陈述句：为什么。。

fundamentally: You use fundamentally for emphasis when you are stating an opinion, or when you are making an important or general statement about something. 从根本上讲，强调

knapsack：A knapsack is a cloth or leather bag that you carry on your back or over your shoulder背包
parachute：降落伞

未完待续
（配音没有字幕的请留言）