IN 1778, HE ……….TO LONDON TO STUDY A. WERE CONDUCTINGWITH BENJAMIN...

15.In 1778, he ……….to London to study

a. were conducting

with Benjamin West for four years.

b. have been conducted

a. has gone

c. had been conducted

b. had gone

d. being conducted

c. would go

22………….billions and billions of stars

exist in the vast space beyond our Milky

d. went