下列与细胞免疫无关的为( ) A．外毒素中和作用 B．抗肿瘤免疫作用 C．移植排斥

小青看到太阳光经过三棱镜后，被分解成各种颜色的光，这是光的______现象，她戴的近视眼镜对光线有______（选填“发散”或“会聚”）作用．

按梅的品种可将梅分为哪几个系？

Don't be angry with us. We ________ with you together, but we were busy with our final reports when you called in.

A．would eat out

B．must have eaten out

C．should eat out

D．could have eaten out

10kV电流互感器二次绕组K2端要可靠接地。

Wi-Fi技术802.11B标准，工作频段在2.4GHz，工作频率带宽为83.5MHz，划分为14个子频道，每个子频道带宽为（）MHz。

A.6

B.11

C.22

D.28