The manager should have arrived ______ (by, until) now.
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This is a race stamp ______ (of, from) my father"s collection.
The little boy hid himself ______ the table.
一等水头变速滤池，分4格，设计滤速为8m/h，正常过滤时，第1格滤速为6m/h，第2格滤速为10m/h，当第1格滤池反冲洗时，如果过滤总流量不变，且滤速按相等比例增加时，第2格滤池的滤速为（）m/h。
A. 13.3
B. 12.3
C. 12
D. 10
My sister is two years ______ (old) than I.
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