Saturated fats have more than one double bond

A、1:1:1

B、1:4:1

C、4:1:1

D、1:1:4

Questions 1 to 5 are based on the following passage:

In the past, operations were difficult. Until the middle of the eighteen fifties, surgery.

In some countries, up to 90 percent of patients died from infection after operations. In 1865, however, Joseph Lister, a British surgeon, found an answer to the problem. He used an “antiseptic” during and after operations. This killed the dangerous bacteria and most of his patients lived. Since then, surgeons have used antiseptics in all operations. Surgery has developed in many important ways since the day of Joseph Lister. Today, when patients go to hospital for an operation, they can expect the best treatment, in clean and hygienic conditions.

Operations were difficult and dangerous until_______.

A.1850

B.the middle of 1850

C.the middle of the fifties of the eighteenth century

D.the middle of the fifties of the nineteenth century

In the passage, surgery means__________.A.The performing of an operation

B.cure

C.treatment

D.medicine

Which topic of the following best suits the passage？A.Operations were difficult in the past

B.The devotion of Joseph Lister to medical science

C.Surgery has become safer

D.Developments in surgery

Joseph Lister was________.A.a Frenchman

B.a German

C.an Englishman

D.an American

In the past, up to 90 percent of patients died after operations mainly because__________.A.bacteria entered the cuts in the patients’ bodies and infection took place

B.the conditions in hospitals were bad

C.the skill of surgeons was not so good

D.there were no good medicine at that time

A、Carbon, Hydrogen, Oxygen

B、Carbon, Hydrogen, Nitrogen

C、Hydrogen, Oxygen, Nitrogen

D、Hydrogen, Nitrogen, Fluoride

A、10-20%

B、15-30%

C、20-35%

D、45-60%