1.Jill and Katy _________________________with their class tomrrowA\are going to swimming B\are going swimming C\ go to swimming D\go swimming2.They promised————————————the work in three daysAto finishB finishingCfinishesDfinished3.若b+c分之一=1.c+a分之一=1,求b分之ab+1

1. D; 2. A;

3.   bc+1=c, ac+1=a. c=1/(1-b) then a/(1-b)+1=a, that is a+1-b=a-ab. then ab+1=b. (ab+1)/b=1 

1. A  are going to swimming       （  be  going  to  结构  ）
   

2. A  to finish                        （in three days 确定时态）

3. 差点把意思理解错了。应该是若b+1/c=1.c+1/a=1，求(ab+1)/b=? 吧

   由1式得c=1/(1-b)

      代入 2式 得  1/(1-b)  +1/a=1

   通分 (a+1-b)/a*(1-b)=1

           a+1-b=a-ab

   转化得ab+1=b  

   所以(ab+1)/b=1

1. A   2.A   3.是b+（1/c）=1，  c+（1/a）=1求（ab+1)/b 吗？

D \go swimming
Ato finish
由b+1/c=1，得：b=1-1/c=(c-1)/c，则1/b=c/(c-1)，
由c+1/a=1，得：1/a=1-c，则a=1/(1-c)，
所以
b分之ab+1
=a+1/b
=1/(1-c)+c/(c-1)
=1/(1-c)-c/(1-c)
=(1-c)/(1-c)
=1

A be going to do sth. 将来做某事  

A  promise to do sht. 承诺做某事

1

由b+1/c=1

得：b=1-1/c=(c-1)/c,则1/b=c/(c-1),
由c+1/a=1

得：1/a=1-c,则a=1/(1-c),
因此
b/(ab+1)

=a+1/b
=1/(1-c)+c/(c-1)
=1/(1-c)-c/(1-c)
=(1-c)/(1-c)
=1