振颤类手法
参考答案：
是指以较高频率进行节律性的轻重交替的刺激，持续作用于人体，使之产生颤动感的一类手法。
_____ as much as one-fifth of the trees have been cut down. [ ]
A. said
B. It said
C. It is said that
D. As is said
根据水合物的生产条件及实际情况，若站内管线已经冰堵，则可以通过（）解决。
A.开水烫
B.火烤
C.加水合物抑制剂
D.都可以
