1、题目3:{an}是等差数列,若a2=3,a7=13,则此数列前8项和为( )

A. 　easy

B. 　easier

C. 　the easiest

D. 　very easy

A. 　though

B. 　before

C. 　because

D. 　since

A. 　a

B. 　an

C. 　the

D. 　/

A. 　How far

B. 　How much

C. 　How often

D. 　How soon

A. 0

B. 1

C. -1

D. 　不存在

A. 　make

B. 　made

C. 　makes

D. 　making

A. 4

B. 3

C. 2

D. 1

A. 　Anything

B. 　Something

C. 　Nothing

D. 　Other things

A. 　famous

B. 　more famous

C. 　most famous

D. 　the most famous

A. 　can

B. 　must

C. 　may

D. 　need