进行室外给水管道两侧回填时，管道两侧应对称回填，防止管道产生位移。( )
参考答案：对
29．Internet，as well as newspapers and magazines，____an inportant part in our daily life．
A．have played
B．are playing
C．is playing
D．has been played
只有T细胞才具有的表面标记为
A．识别抗原受体
B．C3受体
C．细胞因子受体
D．CD3分子
E．有丝分裂原受体
