气性坏疽的致病菌是（）
A.破伤风杆菌
B.溶血性链球菌
C.梭状芽孢杆菌
D.埃希杆菌
E.变形杆菌
参考答案：C
After ten years abroad, he still recognized his old colleagues ________ he set foot in China．
A．immediately
B．for the first time
C．while
D．moment
简述创造性思维及其特征。
