19世纪中叶，马克思恩格斯把社会主义由空想变为科学，奠定这一飞跃的理论基石是（）。

A．against

B．again

C．to

A．against

B．again

C．to

A．Hepatitis A virus

B．Hepatitis B virus

C．Hepatitis C virus

D．Hepatitis D virus

What is known about the influenza virus？

A. It was first found in a group of very old birds.

B. All the different strains can be found in wild birds.

C. It existed over 100 million years ago.

D. It can survive in many different places.

A New Medicine to Treat Both AIDS and Hepatitis B

A medicine approved last month to treat AＩDS (爱滋病) also shows promise against hepatitis B (乙型肝炎).

The drug, 3TC, puts down the hepatitis B virus in people with chronic infections, stopping its damage to the liver, researchers reported.

About one million Americans are thought to be infected with hepatitis B, which can lead to cirrhosis (肝硬化), liver failure and liver cancer in a small proportion of victims if left untreated.＿＿＿＿＿＿＿(46)

"It's a preliminary study, but this is promising, it looks like it has the potential to make a significant impact on hepatitis B," said Dr Jules L. Dienstag of Massachusetts General Hospital, who directed the study.

Currently, the only treatment for hepatitis B is interferon (干扰素). Such a treatment can permanently eliminate the virus in about one-third of patients. ＿＿＿＿＿＿(47)

In the latest study, doctors found that 3TC appeared to knock out the virus

permanently in about 20% of patients when given for three months.＿＿＿＿(48)

Unlike interferon, 3TC is given in pill form. and carries few side effects. The drug was approved by the Food and Drug Administration in November for use against AIDS.

Both the hepatitis B virus and the AIDS virus need a protein to reproduce.

＿＿＿＿＿(49) Doctors have tested similar AIDS drugs against hepatitis B． But all except 3TC have turned out to be ineffective or too toxic (有毒的).

Dr Jay Hoofnagle of the National Institutes of Health said a next step will be to combine 3TC with interferon to see if the two drugs together improve the chance of curing hepatitis B． "It looks extremely promising," he said of 3TC． ＿＿＿＿＿(50)

A． 3TC is One of a group of drugs that block production of this protein.

B．Interferon must be injected for four to six months and often has unpleasant side effects, including flu-like symptoms, fatigue and depression.

C． The hospital is among the biggest ones in America.

D．Dienstag said he hopes that with longer treatment, this response rate can be

doubled.

E． "It's not the answer, but it's a step in the right direction."

F． Perhaps 20% of these patients have lingering (迁延性的) infections that would benefit from treatment.

第 46 题 请选择（46）处的最佳答案．

A．Hepatitis B virus carriers

B．Chronic hepatitis B

C．Hepatitis B related liver cancer

D．Hepatitis B cirrhosis

A．4

B．1b

C．3

D．2

What is known about the influenza virus？

A．It was first found in a group of very old birds.

B．All the different strains can be found in wild birds.

C．It existed over 100 million years ago.

D．It can survive in many different places.