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【单选题】
施工现场设立的安全警示标志，( )，晚上为点红灯在铁路、桥梁及有船只航行的河道附近作业，应避免使用这两类信号标志。A.
插红旗
B.
红灯
C.
黄旗
D.
其他
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【简答题】有一个晶闸管直流调压系统，如图5-15所示。已知U 2 =U' 2 =220V，α 1 =30°，β Ⅱ =60°，求U d 等于多少?若α 1 不变，βⅡ=60°，则U d 等于多少?若电阻R d = 10Ω，求两种情况下电源所供给的有功功率和无功功率各为多少?
【单选题】By 1,800 about half the population of Brazil had come from Africa. So had about half the population of Venezuela. So had a smaller but still large part of all the population of Trans-Atlantic republic...
A.
much less harsh and painful
B.
rather harsh and painful
C.
more harsh and painful
D.
not much less harsh and painful
【简答题】移动电子商务是利用手机、平板电脑等移动终端结合互联、移动通讯技术、 ______________ 、及其他信息处理技术进行的商贸活动。
【单选题】I came by sea and I had a 1ovelyjourney on Queen ElizabethII ．
A.
．不填； the
B.
． the ；不填
C.
．不填：不填
D.
． the ； the
【单选题】My brother had a cold last week, _________.
A.
so had I
B.
so did I
C.
I had so
D.
so I had
【单选题】If I had had enough time, I ____my work.
A.
would finish
B.
must have finished
C.
would have finished
D.
had finished
【简答题】人文地理学的发展可以明显地划分为三个时期:古代的人文地理学、 近代的人文地理学和____。
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