Mina believed that faster reading meant never stopping. While she could move through a page quickly, she often missed words such as only, however, and unless. Her teacher gave her two short passages and asked her to pause only at a change in direction or condition. While Mina read the first passage, she marked one contrast and one limit. Her total reading time increased by less than a minute, but her explanation of the writer's claim became more accurate. The two uses of while do different jobs. The first contrasts speed with missed conditions; the second places the marking activity during the reading. Treating both as a simple time signal would hide the first sentence's concession. Treating both as contrast would distort the sequence of the practice. A reader should test whether the clauses describe simultaneous events or opposing facts, and then check which relation supports the paragraph's main point.