The group of research workers are said to ________ to the dangerous nuclear radiation while they carried out their rescue task.

A. be exposed          B. have been exposed       C. exposed       D. be exposing

The group of research workers are said to ________ to the dangerous nuclear radiation while they carried out their rescue task

1. A.
   be exposed
2. B.
   have been exposed
3. C.
   exposed
4. D.
   be exposing

The group of research workers are said to ________ to the dangerous nuclear radiation while they carried out their rescue task.

A. be exposed　　　　 B. have been exposed　　　 C. exposed　　　 D. be exposing

The group of research workers are said to ________ to the dangerous nuclear radiation while they carried out their rescue task.