麦芽干燥至水分（）％时，停止加热，出炉后必须及时除根，因为麦根带有不良苦味而且吸湿性强。
参考答案：3～5
We have been excavating layers of ash almost six metres thick, which suggests that they________the fire burning all winter.
A．should keep
B．might have kept
C．should have kept
D．might keep
层流现象
