Precipitates are usually collected by centrifugation at intervals.常常是用离心法分段收集沉淀的.Try to get into the habit of eating at least three small meals a day, at equally spaced intervals.尽量养成每天至少吃3顿小餐的习惯，而且每餐的间隔要相同。She began to ...
阿姆斯特朗在离目的地还有300米的地方被堵住不能动弹。Armstrong was boxed in with 300 metres to go.阿姆斯特朗将球打入球门网顶。Armstrong drove the ball into the roof of the net.路易斯·阿姆斯特朗把爵士乐简明扼要地定义为“我一门糊口的手艺”。Louis Armstrong defined jazz pithily as "what I play...