一物体作简谐振动，振动方程为x=Acos（wt+1/4π），在t=T/4（T为周期）时刻，物体的加速度为（）
A.
B.
C.
D.
参考答案：B
给下列复合句中的定语从句填上正确的介词和关系代词。
1. We saw several natives advancing towards our party, and one of them came up to us we gave some bells and glasses.
2.1 was given three books on cooking, the first I really enjoyed.
3. The students visited the farm the farmers raise varieties of beef cattle.
4. The gym the gymnast is doing gymnastics is a newly-built one.
一直都没有用社保卡，现想查询一下余额，不知如何查询？能否在网上查到？
