1。I knew if I kept at it I should succeed.
我知道如果我堅持下去就會成功。
2。You should take advantage of it.
妳應該好好利用這個機會。
下面的用法可能妳已經知道，should對過去的猜測,用法;should have done
e.g. They should have finished it .他們應該是已經做完了。