past passed
past ：gone by or history 经过，过去、以往。
例：The car drove past my house.
My past is very interesting.
passed：pass的过去时态。
例：We passed through the town without stopping.
principal principle
principal：the head of a school 校长
例：The principal spoke to us today.
principle：a principle is an important fact or law.
例：The principle of democracy is important to ourcountry.
