Water precipitates camphor from its alcoholic solution.水能把樟脑从其酒精溶液中淀析出来.Precipitates are usually collected by centrifugation at intervals.常常是用离心法分段收集沉淀的.This important carbide precipitates both inter and intragranularly....
The boy had the presence of mind to turn off the gas.那男孩子镇定地关掉了煤气。He had the presence of mind to put his emergency oxygen tube in his mouth.他镇定自若地把应急输氧管放进了自己的嘴里。I had much presence of mind to bring myself off.我十分镇静地逃了出来....