AM和VSB各是什么调幅方式?各有什么特点?有哪些应用?
参考答案:
都是幅度调制。
AM保留了两个完整的边带,而VSB只保留了一个完整边带和一个不完整的边带,即残留边带。
Tom needs some help ________ his homework. Can you help ________?
A.to, he
B.with, him
C.to, his
D.with, his
触诊腹壁呈揉面感的是()
A.胃肠穿孔
B.肝脾破裂
C.结核性腹膜炎
D.急性腹膜炎
E.急性胰腺炎