如图甲所示,魔术箱内有一个平面镜,从P处放入一物,箱中不见物体;换从Q处放入,箱中却见两个物体.图乙中A'B'是物体AB在平面镜中的像,根据平面镜成像特点,画出物体AB.
. In China, a number of people__________English now, and the number __________growing year after year.
A.studies, is
B.are studying, is
C.is studying, is
D.is studying, are
以下不属于网络安全控制技术的是______。
A.防火墙技术
B.访问控制技术
C.入侵检测技术
D.差错控制技术