气—固相催化反应的内扩散模数的大小可判别内扩散的影响程度，内扩散模数愈小，内外浓度愈近于()

Part B (10 points)You are going to read a text about different types of friendship, followed by a list of examples. Choose the best example from the list for each numbered subheading.I was thinking about how everybody can't be everything to each other, but some people can be something to each other, thank God, from the ones whose shoulder you cry on to the ones whose half slips you borrow to the nameless ones you chat with in the grocery line.(41) Buddies:They are the workhorses of the friendship world. They are the people out there on the front lines, defending you from loneliness and boredom.(42) Working Friend:Then there is that special guy at work. Like all the other people at the job site al first he's just part of the scenery. But gradually he starts to stand out from the crowd.(43) A Faraway FriendHe she is someone you grew up with or went to school with or lived in the same town as until one of you moved away.(44) The Former Friend: 点击查看答案

若砂子的筛分曲线位于规定的三个级配区的某一区，则表明（）

A、砂的级配合格，适合用于配制混凝土
B、砂的细度模数合格，适合用于配制混凝土
C、只能说明砂的级配合格，能否用于配制混凝土还不确定
D、只能说明砂的细度合适，能否用于配制混凝土还不确定

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