LTE中有哪些类型的位置更新？

若（x²-3x+4）（x²-ax+1）的展开式中，含x²项的系数为-1，则a的值是（    ）．

第三部分 情景对话  根据对话内容从题后选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。(5分 每小题1 分)

__The class will be over, Any questions?

_________56_______

__For today’s homework, you should do the exercise on page 10.

_______57______

__First write them down in your exercise books, and then practice them orally until you have learned all of them by heart.

__________58_________

__ I won’t ask you to hand in your exercise books until the day after tomorrow. Can you manage to recite them next week? I think you have plenty of time.

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__ OK. If you have any questions, come to my office tomorrow. I’ll be available from 1:30 to 5:30.

__ Thank you very much._____________60_______

__ You are welcome.

A．Shall we do it orally or write out the exercise in our exercise books?

B．It is difficult for us to finish so much work in such a short time .

C．Mr. Gao, what’s today’s homework?

D．Well, we’ll try to finish the homework in time .E.We’ll go if we have any questions.

F.It will take us a lot of time.

G.We’re wasting too much time.

阅读侯方域《马伶传》中的一段文字，然后回答下面小题。

其夜，华林部过马伶曰：“子，天下之善技也，然无以易李伶。李伶之为严相国至矣，子又安从授之而掩其上哉”马伶曰：“固然，天下无以易李伶，李伶即又不肯授我。我闻今相国昆山顾秉谦者，严相国俦也。我走京师，求为其门卒三年。 日侍相国于朝房，察其举止，聆其语言，久乃得之。此吾之所为师也。”华林部相与罗拜而去。

……

侯方域曰：异哉!马伶之自得师也。夫其以李伶为绝技，无所于求，乃走事昆山，见昆山犹之见分宜也，以分宜教分宜，安得不工哉呜呼!耻其技之不若，而去数千里，为卒三年。倘三年犹不得，即犹不归尔。其志如此，技之工又须问耶

这段文字赞扬了马伶怎样的从艺精神？

赵安中先生在什么事件后，被迫辍学？（）

A.七·七事变

B.五·四运动

C.八·一事变

D.九·一八事变

某DNA片段中胸腺嘧啶的比例为a，则该DNA片段中含有鸟嘌呤的碱基对占所有碱基对的比例是（）

A.a

B.

C.

D.