a. between
b. from
c. of
d. for
a. was sent
b. were sent
c. sented
d. sent
a. is
b. are
c. have
d. do
a. have
c. do
d. many
a. are fly
b. flew
c. are flown
d. flying
a. fly
b. will fly
c. will be flown
d. will flying
a. did fly
b. were flown
c. flew
a. is singing
b. has sung
c. was being sung
d. is being sung
a. making
b. is making
c. is made
d. is being made
a. for
b. in
c. about
d. at
a. is launched
b. is launch
c. is being launch
d. is being launched
b. are flown
c. are flying
d. are being flown
a. was asked
b. asked
c. had asked
d. asking
a. has
b. have
c. is
d. are
a. might
b. may
c. will
d. can