A.Tần số âm.
B.Độ to của âm.
C.Độ cao của âm.
D.Âm sắc.

A.easy
B.complicated
C.different
D.detailed

A.bad and good
B.thick and thin
C.odds and ends
D.high and low

A.conduct
B.condense
C.contest
D.convene

A.did you do
B.were you doing
C.would you do
D.had you done

A.did you do
B.were you doing
C.would you do
D.had you done

A.feature
B.measure
C.feather
D.pleasure

A.hoped
B.gathered
C.remained
D.received

A.hoped
B.gathered
C.remained
D.received

A.It is understood that Ben wants to train to be a pilot.
B.It is to understand that Ben wants to train to be a pilot.
C.It understands that Ben wants to train to be a pilot.
D.Ben understands that he wants to train to be a pilot.