移民流行病学是通过比较()、()和()的某病发病率或()差别,分析该病的发生与()和()的关系。
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布放吊线时,发现吊线有跳股、绞合松散等有损于吊线()的伤残,应剪除后接续再布放。
如果操作时加拔键器拉曲柄键也拉不动,可用吊车或手拉葫芦调节角度直至将键拉出键槽。
A. 正确
B. 错误
An alarm device inserted between the deaerating tank and the expansion tank can notify the on-watching crew that ()
A. the expansion tank is lack of water
B. the expansion tank is over flowing
C. there is something wrong with the cooling system
D. there is something wrong with the engine
某日,正在营业的服装城着火,火势越来越大,扑灭困难,商场应立即拨打()火警电话。
A. 120
B. 119
C. 110