在信息传输速率不变的情况下,4ASK的码元传输速率是2ASK的()倍。 A: 2 B: 1/2 C: 4 D: 1/4

若某4ASK数字调制系统的信息速率为W bit/s，基带信号采用矩形脉冲，则4ASK信号的谱零点带宽为 。

Listen to the conversation and finish the following 4 questions. What does the little boy NOT ask for Christmas? (  )

Pair 4 4.1 When I saw the smoke, I called the fire station to ask them to come immediately. 4.2 When I saw the smoke, I called the fire station to ask the ______ to come immediately.

Passengers ______ to fasten their belts. A: ask B: will ask C: to ask D: are asked

I ______ a question. I did not ______ an answer. A: asked……ask for B: asked……ask C: asked for……ask for D: asked for……ask

Q 4 What question does a child often ask his father? The question is: “What________________do you do, Daddy?”

The student is shy and he ______ questions in class. A: dares not ask B: does not dare to ask C: dares not to ask D: does not dare ask

若某4ASK数字调制系统的信息速率为Wbit/s，基带信号采用矩形脉冲，则4ASK信号的谱零点带宽为。 A: 4W(Hz) B: W(Hz) C: 2W(Hz) D: 0.5W(Hz)

6. Don't be afraid to______advice about things you are not good at. A: ask for B: ask to C: ask about D: ask out