A. if;when B. if; as long as C. whether; as long as D. whether; since
A. one B. that C. ones D. those
A. It was B. That was C. Although D. When
A. keep B. have C. last D. go
A. burst B. went C. fell D. exploded
A. up B. up to C. on D. in
A. came across B. came about C. came after D. came at
A. in B. at C. from D. with
A. playing B. play C. played D. to play
A. has ecome infected B. has become infecting C. had become infected D. had become infecting
A. build B. build into C. build on D. build up
A. must not have B. couldn’t have C. may not have D. can’t have
A. in... to make B. about... to make C. in... making D. about... making