激光焊接可获得深宽比（）的焊缝，焊接厚件时可不开坡口，一次成形。A、小 B、大

M: The taxi driver must have been speeding.
W: Well, not really. He crashed into the tree because he was trying not to hit a box that had fallen off the truck ahead of him.
Question: What do we learn about the taxi driver

A. He turned suddenly and ran into a tree.
B. He was hit by a fallen box from a truck.
C. He drove too fast and crashed into a truck.
D. He was trying to overtake the truck ahead of him.

阅读下列材料，回答问题：

材料一：“诸不在六艺之科孔子之术者，皆绝其道勿使并进。——董仲舒

材料二：“兴太学，置明师，以养天下之士。”

（1）“六艺之科孔子之术”是指哪家的学说？

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（2）这是董仲舒向谁提出的建议？得到采纳了没有？为什么？

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（3）材料二说明统治者采取了什么措施？

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（4）你如何看待材料一、二所叙述的事件？

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用一种试剂区分氯化钠、烧碱、硝酸钡三种无色溶液，应选用（　　）

A．酚酞试液

B．CuSO₄溶液

C．CuCl₂溶液

D．Na₂CO₃溶液

两个相同容积的瓶子装满酒精溶液，一个瓶子中酒精与水的体积比是3:1，另一个瓶子中酒精与水的体积比是4:1。若把两瓶酒精溶液混合，则混合后的酒精和水的体积之比是多少( )

A．31:9
B．7:2
C．31:40
D．20:11

子囊菌中双核阶段较长，而担子菌中双核阶段存在时间较短。（）