you'd better go to Beijing by train,for the train ticket is_____you'd better go to Beijing by train,for the train ticket is_____the plane ticket.A.as cheap three times as B.three times cheaper thanC.as three times cheap as D.cheaper three times thanA

you'd better go to Beijing by train,for the train ticket is_____you'd better go to Beijing by train,for the train ticket is_____the plane ticket.A.as cheap three times as B.three times cheaper thanC.as three times cheap as D.cheaper three times thanA
you'd better go to Beijing by train,for the train ticket is_____
you'd better go to Beijing by train,for the train ticket is_____the plane ticket.
A.as cheap three times as B.three times cheaper than
C.as three times cheap as D.cheaper three times than
At a rough estimate,Nigeria is _____Great Britain.
A.three times the size as B.the size three times of
C.three times as th size of D.three times the size of
讲一下语法,好的会追加分数

you'd better go to Beijing by train,for the train ticket is_____you'd better go to Beijing by train,for the train ticket is_____the plane ticket.A.as cheap three times as B.three times cheaper thanC.as three times cheap as D.cheaper three times thanA
1.B.three times cheaper than
解析：
1）表示比...大/小几倍 —— 数词 + times + 形容词比较级 + than
如：火车票比飞机票便宜三倍
the train ticket is three times cheaper than the plane ticket
2）表示是...的几倍 —— as + 数词 + times + 形容词原级 + as
如：飞机票是火车票的三倍
the plane ticket is as three times expensive as train ticket.
或者：the train ticket is three times cheap as the plane ticket.
2.D.three times the size of
解析：
1）表示 A 和 B 一样大小 —— A is the size of B
如：这个盒子和那一个一样大
This box is the size of that one
2）表示 A 和 B 的几倍一样大小 —— A is + 倍数（数词+times）+ the size of B
如：尼日利亚是英国的三倍大
Nigeria is three times the size of Great Britain.