1. B 这是省掉if的非真实条件从句：当if从句中的谓语部分含有should, had或were时,可以省略if,然后should, had或were 提到主语之前.这个句子加上if,就是. if you were to take the train,you would get there much sonner.
2. C deer 单复数同形,jewellery集合名词,jewel珠宝
3. A 当指代一个句子时,引导词只能用which或as,当从句位于句首时用as,当从句位于主句之后时,用which.这个句子倒过来是这样的：the earth runs around the sun, which
is known to everyone