【句子】

Although pecans are most plentiful in the southeastern part of the United States, they are found as far north as Ohio and Illinois.

虽然美洲山河桃树最集中于美国的东南部但是在北至俄亥俄州及伊利诺斯州也能看见它们 。

【解析】
1.although和though的区别，用法

1)两词同义并可换用，但although语气较重，通常放在句首并用于正式场合

①I'd quite like to go out, (al)though it is a bit late.
我很想外出，虽然为时稍晚。。

②Although it was snowing, it was not very cold.
虽然下着雪，但并不很冷。

2)用though 时，可将强调的词前置，但although 不能。as也有此种倒装结构。

①Poor though / as he is , he is happy.
虽然他穷，但过得很愉快。

②Child though / as she was, the actress was drawing a crowd.
尽管还是个孩子，这个女演员却引起了人们的注目。（child前无冠词a）

3)although 和 though 用作连词时不能和but连用，但可跟yet, still 等连用。

Although he lives alone, yet he is happy.
= He lives alone, but he is happy.
他虽然单独生活，但很愉快。

2. as far as

1)“与……一样远”“一直到……” (在否定句中也可用 so far as)

We didn’t go as [so] far as the others.
我们走得不如其他人远。

2)“就……而言”“从……来看”“尽……所能”“只要”(有时可用 so far as)

As [So] far as I know, that is highly unlikely.
就我所知，那是极不可能的。 

【练习】

Just use this room for the time being, and we’ll offer you a larger one _______it becomes available（10安徽33）
A. as soon as  B. unless  C. as far as  D. until