绿色应用于各种提示标志、车间厂房内的安全通道、行人和车辆的通行标志、消防疏散通道和其他安全防护设备标志、机器启动按钮及安全信号旗等。
参考答案:对
Not only Jim but also my parents and I ______ a few places of interest since we came to China.
A.has visited
B.will visit
C.have visited
D.visited
活塞环与环槽两侧的间隙称为()。