classes: lecturer. It is recommended to install additional curtains in the classroom windows, so that the projector can see more clearly. curriculum. It is recommended to install additional curtains in the classroom windows, so that the projector can see more clearly. facility. It is recommended to install additional curtains in the classroom windows, so that the projector can see more clearly. general. It is recommended to install additional curtains in the classroom windows, so that the projector can see more clearly.