以要约承诺方式订立的合同，合同的有效成立时间是( )。 A．要约到达受要约人前

阅读短文回答问题。

     What do 17-year-old boys usually do ? Play computer games, read books or play basketball? But to

Zac , all interests in   his  life are from the sea. He is a 17-year-old  US  sailor.   After  a   hard 13-month

voyage, he and his 11-metre sailboat arrived at a Southern California harbour. He becomes the youngest

person to sail around the world alone.  

     When Zac was just a child, he had a dream-driving his own boat to travel around the world . so he

saved all his pocket money . When he was 16 years old, he had 6,500 dollars. He bought a sailboat, and

started his journey with the support of his father, a ship builder.

     On June 14, 2008, Zac left Marin Del Rey, south of Los Angeles, and celebrated his 17th birthday at

sea near Africa's Cape of Good Hope.

     During his 28,000-mile journey , he came over many difficulties. When he came back home , he was

welcomed by a lot of people. It is said fewer than  250 People  have sailed around the world alone. The

number of reaching the top of Mount Everest is three  times as large  as the number of sailing around the

world alone.  

参考词汇:voyage航海    harbour 港湾    sail 航行  Mount Everest珠穆朗玛峰  

Cape of Good Hope 好望角

1.Where are Zac's interests from?

______________________________________________________________________

2.How long did he spend in traveling around the world?

______________________________________________________________________

3.What was his father's job?

______________________________________________________________________

4. Was his journey difficult?

______________________________________________________________________

5. Which number is smaller ,the number of reaching the top of Mount Everest or the number of sailing

around the world alone?

______________________________________________________________________

男，38岁，因腰痛伴右下肢放射痛急性发作4天，疼痛加重而入院。查体：下腰椎旁压痛，右直腿抬高试验50°，加强试验(+)，足外侧皮肤感觉麻木，右足跖屈肌力减弱，踝反射消失，诊断为腰椎间盘突出症。

为进一步明确诊断，提高对腰椎间盘突出诊断的精确性，必要的特殊检查是()

A．椎管造影

B．B超检查

C．MRI检查或CT检查

D．腰椎X线片

E．可视性椎间盘造影

关于术后肺不张的叙述，以下哪些正确（）。

A、常发生于胸、腹部大手术后

B、术后早期发热

C、颈部气管向患侧偏移

D、患侧呼吸音低或消失

Delphi法的组成要素包括（）。

A.协调人

B.与决策问题有关的专家

C.一套特制的征询调查表和程序

D.决策问题