下列对冠脉血流储备用超声造影测定的叙述，哪一项是错误的A．低剂量药物负荷试验 B．测

完形填空。

John left the United States in 1969 to work in Africa. Africa was hot. When John  1  to the United States in 1979, he said to himself, " It's much  2   here than it was before I left. I'm going to  3  an electric heater (电热器). Besides, everything is much more  4 ."       John went to a store the next day to buy an electric heater. The salesman  5   him three or four  6   kinds and then said, " And this is our best electric heater. It  7  a lot, but it  8  half of your electricity (电), and electricity is very expensive now, isn't it?"      "Yes, it's very expensive," John answered, " and it's becoming  9  every year." He looked at the electric heater carefully, thought for a few seconds and then said, "Well, I'll take  10  of these, then I'll save all of my electricity."

( )1. A. wrote   ( )2. A. hotter   ( )3. A. buy     ( )4. A. modern   ( )5. A. borrowed ( )6. A. old     ( )7. A. has     ( )8. A. saves   ( )9. A. better   ( )10. A. one     B. pointed B. colder   B. see     B. simple   B. lent     B. bad     B. gets     B. needs   B. worse   B. two     C. listened C. better   C. make     C. expensive C. sold     C. same     C. costs     C. becomes   C. hotter   C. four     D. returned   D. noisier     D. sell       D. beautiful   D. showed     D. different   D. brings     D. produces   D. cheaper     D. three

下列化学反应中，属于分解反应的是（　　）

A．S+O₂

点燃  .

SO₂

B．Zn+2HCl═ZnCl₂+H₂↑

C．2HgO

△   .

2Hg+O₂↑

D．Na₂SO₄+BaCl₂═BaSO₄↓+2NaCl

对建设项目的信息进行分类应遵循( )原则，从而使项目信息分类体系能满足不同项目参与方高效信息交换的需要。

A．稳定性 B．兼容性
C．逻辑性
D．可扩展性

有习惯性流产史的女性，再怀孕前应做哪些检查？

什么叫循环短路？是什么原因？怎么判断？如何处理？