What’s the advantage when using the satellites?（）
A. The message can be directed to the desired location
B. The message can follow the earth‟s curvature
C. The quality of message can not be affected by climatic
D. the range of the message extend and the quality of reception is improved
If oil density were greater than water’s, the oil separator （）.
A. did work
B. would work well
C. didnt work
D. wouldnt work
在急性坏死性溃疡性龈炎患者的龈沟内数量增加的厌氧微生物是（）。
A. 梭形芽孢杆菌与螺旋体
B. 梭形杆菌与螺杆菌
C. 梭形杆菌与螺旋体
D. 具核梭形杆菌与螺杆菌
E. 梭形芽孢杆菌与螺杆菌
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