1.one third/half/twice/three times/etc. + as...as...表示倍数
He will be earning only half as much as he used to.
Their house is one third as large as ours.
Her husband is twice as old as as she(is).
This room is three times as large as that one.
2.one third/half/twice/three times/etc. + the...表示倍数
He will be earning only half the amount he used to receive.
The birth rate in the year of 2000 is twice that in 1999.