1、Most student don‘t know what they should do next.（同义句）
Most student don‘t know —— —— ——next.2、They need tosend for the doctor.（画线部分提问,画send for the doctor） —— —— they need —— —— 3、To keep our environment clean and tidy is our duty.（同义句） —— —— our duty —— —— our environment clean and tidy.