—I’d like to invite you to my birthday party this evening.

—Thanks, but ____ I’ll have time I’m not sure at the moment.

A. while       B. whether        C. if       D. when

—I’d like to invite you to my birthday party this evening.

—Thanks, but ____ I’ll have time I’m not sure at the moment.

A. while       B. whether        C. if       D. when

—I’d like to invite you to my birthday party this evening.

—Thanks, but ____ I’ll have time I’m not sure at the moment.

A. while       B. whether        C. if       D. when

—I’d like to invite you to my birthday party this evening.

—Thanks, but ____ I’ll have time I’m not sure at the moment.

1. A.
   while
2. B.
   whether
3. C.
   if
4. D.
   when

—I'd like to invite you to my birthday party this evening．

—Thanks．but         I'll have time I'm not sure at the moment．

A．while          B．whether        C．that              D．when