The main engine is cooled with fresh water ()is added suitable small quantities of chemicals to prevent corrosion. in which。 on which。 to which。 by which。
钳形电流表所指示的电流就是所测导线的实际工作电流。
社会保障制度最早产生于() 美国。 中国。 德国。 日本。
变压器铁芯必须接地,且只允许两点接地。
()during the last repair? Did you have No.4 cylinder repair。 Do you have No.4 cylinder repaired。 Didn’t you have No.4 cylinder repairing。 Didn’t you have No.4 cylinder repaired。
PowerPoint2003中,如想将某张幻灯片中的几个图形同时选中,可以通过()。