题目

  While attending a conference，I returned to my hotel room late one evening．The overhead    light outside my door was burned out and I had 21 finding the keyhole．When I 22 to open    the door，I 23 around the wall for a light switch．I found a plate where a switch was 24 installed(安装)…but no switch!     Not discouraged easily，l remembered 25 a lamp by the bed when I put down my    luggage 26 in the day.I found the bed in the27 and then the lamp，but when I switched it    on，nothing 28 !I thought that perhaps if I opened the curtains I might be able t3．某质点做简谐运动，其位移随时间变化的关系式为x=10sin（$\frac{π}{4}$t+$\frac{π}{6}$）cm，下列说法正确的是（　　）A．该质点振动周期为T=4 sB．该质点振幅A=10cmC．第1s末和第5s末质点的位移相同D．4s内质点通过的路程为40cm