调制型放大器的作用是将直流信号调制成交流信号,再经放大成较强的交流信号,以克服了零点漂移现象。
参考答案:对
B. Cultural corner
Dragon can be friendly or 1______, they can bring good luck or 2_______ death and destruction. For a creature that doesn’t actually exit, that’s 3_____.
In Chinese culture, dragons are 4______and wise, although they can be 5_________. The dragon was closely 6_________ to the royal family. According to popular 7_______, if you were born in the year of the 8_______, you are intelligent, brave and a natural leader.
But in the west, dragons had a different 9__________.
Why10________the dragon have a different character in different parts of the world? Some experts believe it is 11______to the animals the myths grow out of. In the west, the idea of the dragon probably came from the 12______. But in China, the idea of the dragon came from the 13_________, a good sign for 14_________. So the Chinese dragon was a 15_________ of good fortune.
脑膜炎球菌侵入机体繁殖后,因自溶或死亡而释放内毒素,内毒素的主要作用是引起()
A.菌血症
B.血小板解聚
C.血液白细胞减少
D.细菌素产生
E.血管坏死和血栓形成,周围血管出血