粉末样品颗粒过大或过小对德拜花样影响如何？为什么？板状多晶体样品晶粒过大或过小对衍射

大黄、芒硝均具有的功效是（）

A.泻下、清热

B.泻下、利水

C.泻下、逐饮

D.泻下、杀虫

E.泻下、逐瘀

气体状态方程的关系式为（）

A.Pv/T=p₁v₁/T

B.Pt/v=p₁t₁/v₁

C.TV/P=T₁V₁/P₁

D.p₁T/V=Pt/V₁

The questions in this group are based on the content of a passage. After reading the passage, choose the best answer to each question. Answer all questions following the passage on the basis of what is stated or implied in the passage.

One of the best sources modem scholars have for learning about Hellenistic Egypt is the large supply of papyrus fragments that have turned up in the Egyptian desert over the last century. Papyrus is a thick type of paper made from a reedy plant found in Egypt. Papyrus is much tougher than the wood-pulp paper used in modern society; whereas a book produced today will most likely fall apart within a century, there are papyrus fragments that are still legible over 2,000 years after scribes wrote on them.

It is primarily by accident that any of these fragments have survived. Most of the surviving fragments have been found in ancient garbage dumps that were covered over by the desert and preserved in the dry heat. The benefit of this type of archeological find is that these discarded scraps often give us a more accurate picture of the daily lives of ancient Egyptians--their business affairs, personal correspondence, and religious pleas--than the stone engravings and recorded texts that were intended to be passed down to later generations.

One of the most important papyrus discoveries of recent years was the revelation in 2001 that a scrap of papyrus that had been discarded and used to wrap a mummy contained 110 previously unknown epigrams (short, witty poems) by the Hellenistic poet Posidippus (ca. 280-240 B.C.). Posidippus lived in Alexandria and benefited from the support of King Ptolemy II Philadelphos (ruled 284-246 B.C.). These new epigrams have yielded fascinating insight into the court culture and literary sensibilities of early Hellenistic Egypt.

King Ptolemy, of course, was also a sponsor of the famous library of Alexandria, the greatest depository of knowledge in the ancient world. According to the twelfth-century Byzantine writer John Tzetzes, the ancient library contained nearly half a million papyrus scrolls. If that library had not burned down, maybe archeologists today would not have to spend so much of their time sorting through ancient trash!

The author’s primary intention in this passage appears to be which of the following ？（）

A. To shed light on the underappreciated work of the Hellenistic poet Posidippus

B. To compare the relative merits of papyrus, and wood-pulp paper as media for recording information

C. To discuss the ways in which papyrus fragments help scholars learn about Hellenistic Egypt

D. To answer the questions regarding the burning of the library of Alexandria, one of the great mysteries of the ancient world

E. To suggest possibly fruitful paths for future archeological research into Hellenistic Egypt

三辊轴机组施工比较适用于( )水泥混凝土路面的施工。

A．高级公路、一级公路

B．县乡公路

C．二、三、四级公路

D．旅游公路

E．外公路

成人呼吸窘迫综合征的常见死因是（）.

A.自发性气胸

B.DIC

C.纵隔气肿

D.肺水肿

E.多脏器功能衰竭