澶渊之盟在客观上的重要作用是 [ ]
A、消除了民族矛盾
B、导致了北宋的灭亡
C、削弱了契丹势力
D、维持了长期和平
答案：D
I sent for a technician ___ John isn't familiar _____ the computer software they use? [ ]
A. in case, with
B. in case, to
C. as if, for
D. so that, in
HXD3型电力机车辅助变流器的中间直流回路同时给（）V电源充电模块供电。
