重点讲解：
1. blot out 遮住；挡住；遮蔽；
About the time the three climbers were halfway down, clouds blotted out the sun.
当这3个登山者下到半山腰的时候，云层遮住了太阳3.GD9QQ[IP7zb。
2. show up 出现；
Its symptoms typically show up in early childhood. The main characteristics are inattention, hyperactivity and impulsivity.
其症状通常出现于孩童时期早期，主要的特徵是注意力不集中、过动和冲动|Awn.jDeh8;|9=jic。
3. in silhouette 呈侧面影像；呈黑色轮廓像；
Even from behind in silhouette, Billy recognized the figure.
即便看到的只是背影的轮廓，比利还是认出了那个人影W=u]Z@%|LTLO%bB.8MM;。
4. block out 挡住，遮挡（光线）；
Thick chipboard across the window frames blocked out the daylight.
装在窗框上的厚厚的胶合板挡住了白天的光线qk(-csjNUELp,xB。