将盛有氮气和二氧化氮（假设无N2O4）混合气体的试管倒立于水中，经过足够长时间后

生物进化的原因是： [ ]

A．过渡繁殖

B．生物产生了有利的变异

C．可遗传的有利变异

D．有利变异、选择、遗传的综合作用

I left my knife on the ______ /te??bl/ last night, but I forgot it.

A．travel

B．able

C．table

D．terrible

球阀组装后，工作密封和检修密封的止水面接触应严密，用（）mm塞尺检查，不能塞入，否则应研磨处理

A.0.02

B.0.05

C.0.07

D.0.09

Scientists around the world are racing to learn how to rapidly diagnose, treat and stop the spread of a new, deadly disease. SARS — Severe Acute Respiratory Syndrome — was (1) for the first time in February 2003 in Hanoi, (2) since then has infected more than 1,600 people in 15 countries, killing 63. At this (3) , there are more questions than answers surrounding the disease.

Symptoms start (4) a fever over 100.4 degrees F, chills, headache or body (5) . Within a week, the patient has a dry cough, which might (6) to shortness of breath. In 10% to 200% of cases, patients require (7) ventilation to breathe. About 3.5% die from the disease. Symptoms (8) begin in two to seven days, but some reports suggest it (9) take as long as 10 days. Scientists are close to (10) a lab test to diagnose SARS. In the meantime, it is diagnosed by its symptoms. There is no evidence (11) antibiotics or anti-viral medicines help, (12) doctors can offer only supportive care. Patients with SARS are kept in isolation to reduce the risk of (13) . Scientists aren’t sure yet, but some researchers think it’s a (14) discovered coronavirus, the family of viruses that cause some common colds.

Most cases appear to have been passed (15) droplets expelled when infected patients cough or sneeze. Family members of infected people and medical workers who care for them have been most likely to (16) the illness. But recent developments in Hong Kong suggest that the (17) might spread through air, or that the virus might (18) for two to three hours on doorknobs or other (19) Health experts say it is (20) , though, that sharing an elevator briefly with an infected person would be enough to pass the virus.

8（）

A.regularly

B.ordinarily

C.traditionally

D.generally

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