tudouzhang

1.  你应该知道饭后不能立即去游泳。
You know better than to swim immediatly after eating.
2. 你年纪足够大了，应该知道不该把钱全花在买衣服上。
You are old enough to know better than to spend all your money on clothes.
3. 我知道不能借钱给他去赌博
I know better than to lent  him money on gambling.

waihaiss

1.  你应该知道饭后不能立即去游泳。you should kown better than  to go swimming right after eating.
2. 你年纪足够大了，应该知道不该把钱全花在买衣服上。you are old enough to should kown better than to spend your money on  clothes.
3. 我知道不能借钱给他去赌博。 i should kown better than to lend him money to gamble.

mapleleaf

1. You should know better than to go swimming right after eating.
2. You are old enough to know better than to spend all your money on clothes.
3. I know better than to lend him any money to gamble.