单项选择题
A．learn about the change of weather B．group them and give them names C．tell the differences in clouds D．find the likeness of clouds
A．the weather always remains the same in a day B．a fine day can't last for long C．we rarely think about the weather D．the weather changes a lot
A．If clouds are high, there will be bad weather. B．The color of clouds is a factor to help predict the weather. C．If the weather is good, the clouds must be very low. D．To study clouds is the only way to understand the weather.