题目

My father had a union job at a film-processing lab, and layoffs—and eventual rehirings—were common during the 1960s. My mother, however,     1     the family’s finances, and each layoff was extremely     2     . She worked, but money was tight as she     3     to pay the rent and the other bills until my dad was rehired. She always managed to protect my sister and me from the financial     4    , and we never knew the extent of her worries.         5     one spring, when I was 10, during one of my father’s layoffs, I could     6 �18、右图所示对比实验主要探究的燃烧条件是（　　）A、氧气B、可燃物C、使可燃物的温度达到着火点D、以上都是