Timed tet! will mark brainliest which questions would improve the reader’s ability to understand the military leaders’ fear that the code would no longer be effective? check all that apply. how many people spoke navajo before world war i? was the us government able to figure out other countries’ codes? why did the navajos try to prevent outsiders from learning their language? did any of the japanese or german students learn to speak navajo? what kind of code did the american indians use during world war i?