如图所示,一束光线从空气斜射入水中,画出该光线在水中传播的大致方向.
已作出法线,由光从空气斜射入水时,折射角小于入射角的规律作出折射光线,折射光线向法线靠近,如图所示:
This machine is very easy . Anybody can learn to use it in a few minutes. [ ]
A. operating
B. to be operating
C. operated
D. to operate
下列何种疾病的声像图特点呈“双泡征”()
A.胎儿颈部水囊瘤
B.胎儿肝内囊性包块
C.胎儿十二指肠梗阻
D.胎儿脐疝
E.胎儿脑脊膜膨出