— Can you make a snowman?
— I ____________ I can. [ ]
A. know
B. think
C. thank
D. find
答案:B
理想变压器工作时,原线圈一边与副线圈一边相等的物理量是( )
A.电压
B.电流
C.电功率
D.频率
数量最多的免疫器官是().
A.胸腺
B.脾
C.淋巴结
D.骨髓