Before welding in a tank that has carried petroleum products,the tank must be certified by ().
A. the Coast Guard
B. the ABS
C. the shipyard fire department
D. a certified marine chemist
空调系统里,一旦探测到管道超温,则()
A. 混合器风门关;
B. 压力调节活门和所有的配平空气活门都关;
C. 压力调节活门和相应的配平空气活门关
在Dreamweaver中,显示/隐藏属性面板的组合键为()。
J2113B最大锁模力为1250KN,为()类型压铸机,进行第()次重大结构改进。