In the second lesson, the teacher still____him to draw an egg, but he____the egg on a plate. Little Leo____unhappy and asked, "____do we draw eggs all the time?" "Look ____. It's an egg again, but it looks____." said the teacher.
下面措施中,哪一种对保持生态环境最有利?
She felt ____ (embarrass) when she fell down in public.
如图所示,一圆柱形桶的高为d、底面直径 3d .当桶内无液体时,用一细束单色光从某点A沿桶口边缘恰好照射到桶底边缘上的某点B.当桶内液体的深度等于桶高的一半时,仍然从A点沿AB方向照射,恰好照射到桶底上的C点.C、B两点相距 3d3 ,光在真空中的速度c=3.0×108m/s.求:
(i)液体的折射率n;
(ii)光在液体中传播的速度v.
默写填空。