电流互感器副边为什么不能开路？电压互感器副边为什么不能短路？

病历摘要：患者男性，28岁，因劳累后呼吸困难1周入院。既往有心脏病史。PR：心脏向左下扩大，心率120次/分，心率快慢不一，心音强弱不等，胸骨左缘第3、4肋间可闻及3/6级舒张期哈气性递减型杂音，心尖部闻及3/6级舒张期隆隆样杂音。

患者应进一步做哪些检查（）。

A.心电图

B.超声心动图

C.胸片

D.血电解质测定

E.抗"O"

F.血沉；抗DNA酶B

The change was so _____ that we hardly noticed it.

A．actual

B．frequent

C．gradual

D．grateful

引起交叉性感觉障碍的病变部位在

A．丘脑

B．脊髓后根

C．脊髓后角

D．内囊

E．脑干

完形填空（共10小题；每小题２分，满分20分）

阅读下面短文，掌握其大意，然后从21－30各题所给的ABC和D项中，选出最佳选项．

The finest and most sought-after violins were handcrafted by an Italian violin maker over 250 years ago. The man’s name was Antonius Stradivarius. He was born in 1644 and began his career  21  a violin maker’s apprentice (学徒). Working on his own by 1680, he became determined to make   22  that could reproduce tones as rich as those produced by the human voice. He  23    several shapes and styles for his violins until he arrived at a design that pleased him. During his career he crafted 1,100 violins. Those in   24  have become treasured possessions.

Unfortunately, the secret of the Stradivarius violin died with its maker. During his lifetime Stradivarius kept his notes safely   25  , even his two sons, who helped him in his workshop, did not know all the steps involved in each violin’s construction.

Through the years, many experts have offered    26  explanations for the unique tone of a “Strad”. Some say it is due to the violin’s shape. Others suggests that the secret    27  the special properties(特性) of the wood, which Stradivarius obtained from native Italian trees that no longer exist. The most widely accepted explanation is that it is created by the varnish（清漆） that the   28   used to coat his violins. Chemists have analyzed as closely as possible the varnish and have found its   29   has improved the sound of many violins.   30  , no other violin maker has been able to fully reproduce the tone of the Stradivarius’s violins.

21.  A. with                B. as             C. for             D. from

22.  A. Instruments    B. facilities            C. equipment     D. tools

23.  A. investigated     B. surveyed      C. tested          D. experimented

24.  A. fashion             B. existence        C. possession     D. use

25.  A. protected         B. buried        C. hidden        D. covered

26.  A. possible      B. accurate             C. detailed       D. persuasive

27.  A. brings in     B. takes in       C. results in      D. lies in

28.  A. master       B. violinist       C. expert          D. user

29.  A. attention            B. application    C. invention            D. foundation

30.  A. Additionally         B. Luckily        C. Therefore     D. Still

从司法制度角度对本案进行评述。