【经典必背】
If you wish to succeed, you should use persistence as your good friend, experience as your reference, prudence as your brother and hope as your sentry. 如果你希望成功，当以恒心为良友，以经验为参谋，以谨慎为兄弟，以希望为哨兵。
【课文原句】
Chinese doctors believe that they should eat more yin foods like tofu. 中医认为他们应该多吃一些阴性食物，如豆腐。
Mum, I don't think you should buy clothes made of animal fur. 妈妈，我认为你不应该买一些用动物皮制作的衣服。
What do you mean by saying that? You shouldn't shout at me. I didn't want to miss the goal, either. 你那样说是什么意思？你不应该冲我叫嚷。我也不想错过这个进球。
【基础知识】
should是情态动词，是shall的过去式。作为情态动词，后跟动词原形。没有人称和数的变化。在表示提出建议时，比must更委婉、客气。其否定形式在其后加not, 缩写为shouldn't。
1. 情态动词还有：can, may, must, need, could, might, ought (not) to，接动词原形，在情态动词后加not构成否定式。
— Excuse me. How can I get to the railway station? 请问我怎样走可以去火车站？
— Turn left and then follow your nose. You can't miss it! 向左转，一直走，你不会错过的。
Which sign means“We mustn't stop our cars here”？ 哪一个标志的意思是“此处禁止停车”？
Nice to meet you. I'm Sam. May I know your name? 见到你真高兴，我叫萨姆，能告诉我你的名字吗？
2. can/may/must这三个情态动词常用来表示推测，一般接be表示推测。can一般用否定形式，表示主观上对某事物的一种否定的推测，意为“一定不是”；may be表示的可能性只有百分之五十左右；must be表示主观上对某事的一种非常肯定的态度。
— Whose notebook is this? 这是谁的笔记本？
— It must be Carla's. It has her name on it. 一定是卡拉的，上面还有她的名字。
Mr. Wang can't be at home, because the lights are off. 王先生不可能在家，他的屋子里的灯没亮。
He may be on business. 他可能出差去了。