come across
(偶然)遇见,碰见,发现:
I came across children sleeping under bridges.
我偶然发现睡在桥下的孩子。

alternative to
可供选择的事物:
You can be paid in cash weekly or by cheque monthly; those are the two alternatives.
你的工资可以按周以现金支取,或按月以支票支取。二者可选其一。

preferable (to sth / to doing sth)

较适合；更可取:
Anything was preferable to the tense atmosphere at home.
什么都比家里的紧张气氛好。

line sth (with sth)
(用…)做衬里:
Line the pan with greaseproof paper.
在烤盘里垫一层防油纸。

be to
(表示安排或计划时用):
They are to be married in June.
他们计划于六月份结婚。