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 ...
“ 我也没想到, "嘉莉开心地说, 她的脸因为兴奋泛起了红晕." I never did , either,'said Carrie merrily, her face flushed with delight.会不会有人逗你开心地笑?Is it possible for somebody to tease you laughing at joyfully?...