I wrote to my parents once a week,____ I was too busy with my teaching work.

A. it  B. unless   C. when    D. as

. I wrote to my parents once a week,____ I was too busy with my teaching work.

A. it  B. unless   C. when    D. as

I wrote to my parents once a week,____ I was too busy with my teaching work.

A. it  B. unless   C. when    D. as

I wrote to my parents once a week,____ I was too busy with my teaching work.

A. it　　　　　 B. unless　　　 C. when　　　　 D. as

I wrote to my parents once a week,____ I was too busy with my teaching work

1. A.
   it
2. B.
   unless
3. C.
   when
4. D.
   as