That boy comes _____ Tokyo, Japan. [ ]
A. in
B. at
C. of
D. from
答案:D
动线优化遵循的基本原则是“不迂回、不交叉”。()
750kV电抗器,运行油中含气量应该小于等于()%。
A.2
B.3
C.4
D.5