Mr Hall understands that ________ maths has always been easy for him,it is not easy for the studants．

1. A.
   unless
2. B.
   since
3. C.
   although
4. D.
   when

(1)Mr Hall understands that ________ maths has always been easy for him, it is not easy for the students.

[　　]

(2)The manager insisted that the debt ________ before next week.

[　　]

Mr.Hall understands that__________maths has always been easy for him，it is not easy for the students.

A.unless                B.since                  C.although             D.when?

（2010·福建厦门杏南中学高三10月月考）   27. Mr. Hall understands that _______ maths has always been easy for him, it is not easy for the students.

A. unless B. since          C. although     D. when