There are many reasons of the tidal action which is a very complicated phenomenon involving many factors all of which must be considered to predict tide in any one place at any one time. The alternate rise and fall of the surface of the seas and the ocean is mainly caused by the attractive force of the moon alone. When the attraction is great, the tide is high; and conversely when the attraction is minimal, the tide is low. Between the high and the low tide is a period of a little over six hours, being called during its rise a flood tide, and during its fall an ebb tide.
The sun also exerts its effect on the tide, being a lit fie less than half as much as the moon, although its mass is so much greater. When the moon and the sun are horizontal, the highest high tide occurs and when they are vertical the lowest low tide takes place.
The wind also plays an important part in the modification of the normal rise and fall of the tide. Thus these factors affect each other, either detracting or adding to the attractive forces to add or subtract from the weight of the tide. But the tides still move inexorably on, rising twice a day, getting a little later each day and posing a problem of correctly predicting their heights and lows.

A:more than half that of the moon B:more than that of the moon C:more than twice that of the moon D:half that of the moon

B Today there are policemen everywhere, but in 1700, London had no policemen at all. A few old men used to protect the city streets at night and they were not paid. About 300 years ago, London was starting to get bigger and more and more people began to live there. The city was very dirty and many people were poor. There were so many thieves who stole money in the streets that people stayed in their homes as much as possible. In 1750, Henry Fielding started to pay a group of people to stop thieves. They were like policemen and were called "Bow Street Runners" because they worked near Bow Street. Fifty years later, there were 120 "Bow Street Runners", but London had become very big and needed more policemen. So in 1829, the first Metropolitan (or London)Police Force was started with 3,000 officers. Most of the men worked on foot, but a few rode horses. Until 1920 all the police in London were men. Today. the London police are quite well paid and for the few police officers who still ride horses, the pay is even better than for the others. Today, London police officers who ride horses are paid __________.

A:the same as their Workmates B:more than their workmates C:half as much as their workmates D:less than their workmates

Today there are policemen everywhere, but in 1700, London had no policemen at all. A few old men used to protect the city streets at night and they were not paid.
About 300 years ago, London was starting to get bigger and more and more people began to live there. The city was very dirty and many people were poor. There were so many thieves who stole money in the streets that people stayed in their homes as much as possible.
In 1750,Henry Fielding started to pay a group of people to stop thieves. They were like policemen and were called "Bow Street Runners" because they worked near Bow Street.
Fifty years later, there were 120 "Bow Street Runners", but London had become very big and needed more policemen. So in 1829, the first Metropolitan(or London)Police Force was started with 3,000 officers. Most of the men worked on foot, but a few rode horses. Until 1920 all the police in London were men.
Today, London police are quite well paid and for the few police officers who still ride horses, the pay is even better than for the others.
Today, police officers who ride horses are paid ______.

A:the same as their workmates B:more than their workmates C:half as much as their workmates D:less than their workmates

B 　　Today there are policemen everywhere, but in 1700, London had no policemen at all. A few old men used to protect the city streets at night and they were not paid. 　　About 300 years ago, London was starting to get bigger and more and more people began to live there. The city was very dirty and many people were poor. There were so many thieves who stole money in the streets that people stayed in their homes as much as possible. 　　In 1750,Henry Fielding started to pay a group of people to stop thieves. They were like policemen and were called “Bow Street Runners” because they worked near Bow Street. 　　Fifty years later, there were 120 “Bow Street Runners”, but London had become very big and needed more policemen. So in 1829， the first Metropolitan(or London)Police Force was started with 3,000 officers. Most of the men worked on foot, but a few rode horses. Until 1920 all the police in London were men. 　　Today, London police are quite well paid and for the few police officers who still ride horses, the pay is even better than for the others. oday, police officers who ride horses are paid______.

A:the same as their workmates B:more than their workmates C:half as much as their workmates D:less than their workmates

B Today there are policemen everywhere, but in 1700, London had no policemen at all. A few old men used to protect the city streets at night and they were not paid. About 300 years ago, London was starting to get bigger and more and more people began to live there. The city was very dirty and many people were poor. There were so many thieves who stole money in the streets that people stayed in their homes as much as possible. In 1750, Henry Fielding started to pay a group of people to stop thieves. They were like policemen and were called "Bow Street Runners" because they worked near Bow Street. Fifty years later, there were 120 "Bow Street Runners", but London had become very big and needed more policemen. So in 1829, the first Metropolitan (or London)Police Force was started with 3,000 officers. Most of the men worked on foot, but a few rode horses. Until 1920 all the police in London were men. Today. the London police are quite well paid and for the few police officers who still ride horses, the pay is even better than for the others. Today, London police officers who ride horses are paid __________.

A:the same as their Workmates B:more than their workmates C:half as much as their workmates D:less than their workmates

B 　　Today there are policemen everywhere, but in 1700, London had no policemen at all. A few old men used to protect the city streets at night and they were not paid. 　　About 300 years ago, London was starting to get bigger and more and more people began to live there. The city was very dirty and many people were poor. There were so many thieves who stole money in the streets that people stayed in their homes as much as possible. 　　In 1750,Henry Fielding started to pay a group of people to stop thieves. They were like policemen and were called “Bow Street Runners” because they worked near Bow Street. 　　Fifty years later, there were 120 “Bow Street Runners”, but London had become very big and needed more policemen. So in 1829， the first Metropolitan(or London)Police Force was started with 3,000 officers. Most of the men worked on foot, but a few rode horses. Until 1920 all the police in London were men. 　　Today, London police are quite well paid and for the few police officers who still ride horses, the pay is even better than for the others. oday, police officers who ride horses are paid______.

A:the same as their workmates B:more than their workmates C:half as much as their workmates D:less than their workmates

B Today there are policemen everywhere, but in 1700, London had no policemen at all. A few old men used to protect the city streets at night and they were not paid. About 300 years ago, London was starting to get bigger and more and more people began to live there. The city was very dirty and many people were poor. There were so many thieves who stole money in the streets that people stayed in their homes as much as possible. In 1750, Henry Fielding started to pay a group of people to stop thieves. They were like policemen and were called "Bow Street Runners" because they worked near Bow Street. Fifty years later, there were 120 "Bow Street Runners", but London had become very big and needed more policemen. So in 1829, the first Metropolitan (or London)Police Force was started with 3,000 officers. Most of the men worked on foot, but a few rode horses. Until 1920 all the police in London were men. Today. the London police are quite well paid and for the few police officers who still ride horses, the pay is even better than for the others. Today, London police officers who ride horses are paid __________.

A:the same as their Workmates B:more than their workmates C:half as much as their workmates D:less than their workmates