abbr.shall not 不应该(口语的);
例句:
You can talk till all is blue but I shan't believe you.
你可以没完没了地说下去,但是我不会相信你.
By the looks of it, we shan't have much rain this month.
看样子这个月雨水也不会很多.
I shan't be back before tomorrow night.
我要到明天晚上才回来.