简述培养基常压蒸气灭菌法的特点
压蒸气灭菌亦称流通蒸气灭菌，温度一般为100℃或略高。此法优点是设备简单，投资较少，因温度不很高，培养料中养分不易破坏，可大量处理需要灭菌的物品。缺点是灭菌时间长，达100℃后，须持续8个小时以上，方可保证灭菌效果，燃料耗费多。
Ifyouaretoo________ofyourchildren,theywillneverlearntodealwithdifficultiesinlife.
重写句子：WelivedinasmalltownwhenIwasasmallchild.WemovedtoShanghailater.Myfatherlandedabetterjobthere.(compound-complexsentence)
Whilecrossingthemountainarea,allthemencarriedgunslestthey______bywildanimals.
重写句子：NotuntilhecrossedthelineandfeltthetapesnapagainsthischestdidJohnsonknowhehadwontherace.(loosesentence)