Mr. Smith has done some research on wild animals for 20 years.
--- Oh! He must have _________ a lot of difficulties.
A. given in B. cared about C. joined in D. gone through
Mr. Smith has done some research on wild animals for 20 years.
--- Oh! He must have _________ a lot of difficulties.
A. given in B. cared about C. joined in D. gone through
D