Article in English: Baking soda is an effective, natural, and non-abrasive cleanser that can safely remove the rings in your toilet. Simply open a box of baking soda, and sprinkle a generous amount around the bowl of your toilet. Allow the baking soda to begin breaking down your hard water stains by giving it some time to sit. Set a timer, and let the baking soda sit for at least 1 hour. While you wait, place some diluted white vinegar in a spray bottle. Used together, vinegar and baking soda create a powerhouse of natural cleansing. Take your spray bottle of vinegar and spray the inside of your toilet bowl. Use only a small amount of vinegar at a time, and add more as needed. Using a toilet brush, vigorously scrub away your rings. If it is left to sit in your toilet system for too long, vinegar can potentially cause damage to your toilet's inner-workings. In order to prevent this, be sure to flush your toilet at least three times after your scrubbing is done.

Summary in Chinese:
在厕所里撒些小苏打。 等一个小时或更长的时间。 用白醋将小苏打喷湿。 用力擦拭马桶内壁。