进行大气环境影响预测时，在计算( )时，可不考虑SO2的转化。
A．1h平均浓度 B．日平均浓度 C．月平均浓度 D．年平均浓度
参考答案：A
— Look! Mr Hu is on the other side of the stree.
— It ______ be him. He has gone to England. [ ]
A. mustn't
B. can't
C. shouldn't
D. won't
淋巴细胞按其性质和功能可分为几种？
