橡胶塑炼程度越深，橡胶大分子链遭受破坏越大，降低了制品的耐老化性能。
参考答案：对
The boy was sitting on the floor ______ by toys. [ ]
A. fsurrounded
B. surrounding
C. surroundings
D. surround
肛门坐浴治疗的水温要求是（）
A.39～41℃
B.37～39℃
C.41～43℃
D.35～37℃
E.43～46℃
