读一读,画一画。
1. Draw a desk. Colour it yellow.
2. Draw a ball. It's under the desk. Colour it black and white.
3. Draw a book. It's on the desk. Colour it red.
4. Draw a chair. It's behind the desk. Colour it yellow.

请根据题目要求进行绘画：
1. 画一张书桌，涂成黄色。
2. 画一个球，它在书桌下面，涂成黑白相间的颜色。
3. 画一本书，它在书桌上，涂成红色。
4. 画一把椅子，它在书桌后面，涂成黄色。