One of the first things you would have to do is open a checking accant.（)

It is one ________ best sellers in our country now.

[A] of them

[B] of those

[C] of this

[D] of their

A.Yes, I think so

B.It's hard to say

C.Impossible

D.That’s unlikely.

A.A.一 _________________________________-

B.B. This one isn't that expensive and it's near the bus stop.

C.C. Don't you remember？ We both went to Jane's party last week.

D.D. Well,I,d rather have my own plac

What is the 'biggest city in the world？ That is, (21) city has the largest population？ This seems like (22) question to answer, but actually it isn't.

It's actually rather difficult to say which cities (23) the largest. There are two reasons for this difficulty. First of all, it isn't easy to determine a city's boundaries, that is, where a city ends. Nowadays, nearly all cities have a large (24) area around them. So when we talk about the population of a city, we often mean the population of the whole metropolitan area around the city. That means that it's difficult to determine what the population of a city is because it's difficult to define what a city is.

The second reason that it is difficult to 25 the population of different cities is this: it is almost impossible to get (26) about the population of all cities for the same year. For example, we might get an estimate of New York's population in 1979 and an (27) of Mexico City's population in 1981. So we real ly can't compare the numbers because the information is for (28) different years. And the population of cities changes rather quickly, especially in some cases. For example, the population of Jakarta, Indonesia, may increase by 5% each year, so the population figure will change rather quickly.

So we can say that these are our two (29) for comparing the populations of cities: one, it's difficult to determine the (30) of a city, and two, it is difficult to get accurate information.

21. A. what

B. which

C. where

D. how

Researchers have found that REM(rapid eye movement)sleep is important to human beings. This type of sleep generally occurs four or five times during one night of sleep lasting five minutes to forty minutes for each occurrence. The deeper a persons sleep becomes, the longer the periods of rapid eye movement. There are physical changes in the body to show that a person has changed from NREM(non-rapid eye movement)to REM sleep. Breathing becomes faster, the heart rate increases, and, as the name implies, the eyes begin to move quickly. Accompanying these physical changes in the body there is a very important characteristic of REM sleep. It is during REM sleep that a person dreams.

According to the passage, how often does REM sleep occur in one night？

A．Once.

B．Twice.

C．Four or five times.

D．Forty times.

A.one

B.two

C.three

A.twentieth; one

B.twenty; one

C.twentieth; first

D.twenty; first

A.First World War

B.World War the One

C.the First World War

D.the World War One

A.first

B.one

C.second

One attribute of the stack is(72).

A．FIFO(First In First Out)

B．LIFO(Last In First Out)

C．queue

D．built into their circuitry