1.Anyone swimming in this lake is at his own risk.
2.However,what I know is that only love,care,and understanding can build up
an ideal relationship between teachers and students.
3.It's Saturday already.It's high time for you to put down your work.
4.众所周知,为了生存我们食物和水.
5.他们的飞机应该在 15分钟后到达.
答案不唯一