急性乳腺炎最常见于（）
A.妊娠期妇女
B.产后哺乳期妇女
C. * * 凹陷妇女
D.以上都是
E.以上都不是
参考答案：D
（10分）如图所示，一U形金属框的可动边AC长0.1m，匀强磁场的磁感强度为0.5T，AC以8 m/s的速度水平向右移动，电阻R为5 Ω，（其它电阻均不计）．（1）计算感应电动势的大小；（2）求出电阻R中的电流有多大?
Also found in Paragraph 1, what does "this case study" probably refer to
A．A case study the writer is to talk about.
B．Part of a textbook on politics.
C．What the author is going to write.
D．Washington's inability to fool anyone.
