39.
(A) twice as fast as
(B) as twice as fast
(C) fast twice as
(D) as fast twice as V. Dialogue

倍數比一比 

倍數 + as 形容詞 / 副詞 as

My watch is twice as expensive as yours.（我的手錶是你的兩倍價錢。）

The cheetah runs three times as fast as the zebra.（獵豹跑的速度是斑馬的三倍快。）

倍數 + as many 可數名詞 / much 不可數名詞 as

He has half as many jerseysas his brother does.（他有的球衣數量是他哥哥的一半。）

Taking a bath uses three times as much water as taking a shower.（泡澡使用淋浴三倍量的水。）

倍數 + the size / weight / height / number ... of something

My living room is three times the size of yours.（我的客廳是你客廳的三倍大小。）

The Eiffel Tower is about twice the height of the Pyramid of Giza.（巴黎鐵塔是吉薩金字塔的大約兩倍高度。）

倍數 + 形容詞比較級 / 副詞比較級 + than

My watch is twice more expensive than yours.（我的手錶比你的多兩倍價錢。）

The cheetah runs three times faster than the polar bear.（獵豹跑的速度比北極熊快三倍。）
資料來源