若柴油机不能按要求停机，应使用（）或关闭燃油截止阀。
参考答案：紧急停车按钮
（）被认为是衡量啤酒成熟与否的决定性的指标，其味阈值为0．1～0.15mg/L，在啤酒中超过阈值会出现馊饭味。
A．2，3-戊二酮
B．酯类
C．乙醇
D．双乙酰
California seems to be the home of the homeless since many are often observed tramping along railroad tracks and through the downtown areas of the cities.
A．roaming
B．trimming
C．stealing
D．stamping
