HE H A D SO A D I F F I C U L T EXERCISE THAT HE COULDN'T DO IT.A....

64. - 300 CAU TRAC NGHIEM XAC DINH LOI SAI
300 CAU TRAC NGHIEM XAC DINH LOI SAI

64. He h a d so a d i f f i c u l t exercise that he couldn't do it.

a. had

b. so

c. difficult

d. it