阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。学科&网
Hundreds of people have formed impressions of you through that little device(装置) on your desk. And they’ve never actually 41 you. Everything they know about you 42 through this device, sometimes from hundreds of miles away. 43 they feel they can know you 44 from the sound of your voice. That’s how powerful the 45 is.
Powerful, yes, but not always 46 . For years I dealt with my travel agent only by phone. Rani, my faceless agent whom I’d never met 47 , got me rock-bottom prices on airfares, cars, and hotels. But her cold voice really 48 me. I sometimes wished to 49 another agent.
One morning, I had to 50 an immediate flight home for a family emergency. I ran into Rani’s office 51 . The woman sitting at the desk, 52 my madness, sympathetically jumped up. She gave me a 53 smile, nodded while listening patiently, and then printed out the 54 immediately. “What a wonderful lady!” I thought.
Rushing out 55 I called out over my shoulder, “By the way, what’s your name?” “I’m Rani,” she said. I turned around and saw a 56 woman with a big smile on her face waving to wish me a safe trip. I was 57 ! Why had I thought she was cold? Rani was, well, so 58 .
Sitting back in the car on the way to the airport, I figured it all out. Rani’s 59 ---her warm smile, her nods, her ‘I’m here for you’ 60 ---were all silent signals that didn’t travel through wires.
46（）
A. direct
B. useful
C. easy
D. accurate
，因为t=4s时，P点向上振动，故波向左传播；选项A 正确；B错误；0到4.0 s时间内，质点P振动2个周期，通过的路程是8A=8×4cm=32cm=0.32m，选项D 正确，C错误；