According to a study by SallieMae, 84 percent of undergraduate students have credit cards, and by the time they are seniors, they have accumulated US $ 4,100 in debt, on top of whatever student loans they may have taken out．
Credit cards are the most convenient form of payment, and they are aggressively marketed to college students．Reportedly, a typical college student carries 4．6 credit cards and US $ 3,173 in credit card debt．
Credit cards seem to be a fact of life, not just student life． In the long term,  using a credit card properly and paying off the balance can help establish a card history and increase your credit score, which will come in handy when you need an important loan, for a house or car, for example．Your credit score can affect even unrelated things like insurance rates．Credit cards also offer more protection for users than debit cards（借记卡）．Under federal law, the credit card holder is only responsible for the first US  $ 50in fraudulent（欺诈的） purchases in cases of theft or loss．However, debit card users are responsible for the first US $ 500．                                   
SallieMae found some good news in the fact that two thirds of students had discussed credit issues with their parents, but 84 percent said they needed more information．Those who didn't get any guidance were more likely to be surprised when they found out how much they owed．
While credit cards offer the easiest access to money, they make it easy to live outside your means．Less than a fifth of students surveyed paid off their balance every month, and carrying a balance brings finance charges, sometimes at a very high interest rates．
SallieMae found that almost 40 percent of students chose their first credit card based on direct mail, which is probably why students get credit card offers in the mail． But when the credit card offers flow in, be sure that you read the fine print．Offers of low or no interest rates can disappear, leaving you a debt that climbs beyond your ability to pay it off．
What does the first paragraph imply?

A．Most of the senior students are shocked to see how much they owed．

B．Students can only take out loans from credit cards．

C．Most of students' loans come from credit cards．

D．Credit cards have a bad effect on college students．

The underlined part "come in handy" in the third paragraph probably means “         ”

A．bring trouble	B．make mistakes
C．be important	D．be useful

According to SallieMae, what is the possible reason why students get so many credit card offers in the mail?

A．Many students' first credit card is based on direct mail．

B．it costs the banks little to mail out credit cards．

C．Students don't like to go to the bank to open a credit card account．

D．Banks have no other way to let students use their credit cards．

What is the theme of the third paragraph?

A．The advantages of using debit cards．

B．The similarities between credit cards and debit cards．

C．The advantages of using credit cards．

D．Credit cards are the most convenient form of payment．

According to SallieMae, how many students had not discussed credit issues with their parents?

A．l/3

B．2/3

C．l/4

D．3/4