271. Decisions are made as to which information should remain in long-term memory.

英语四级译文:
关于哪些信息应该留存于长期记忆之中的决定已经作出。

四级词汇讲解:
本句的主干是Decisions are made。as to...为句子的状语，其中which引导的是介词to的宾语从句。

make a decision的意思是“作出决定”。如:
I'm really bad at making decisions.我的确不善于决策。

as to的意思是“至于……，提到……”，也可替换为as regards。如:
There are no special rules as tolregards what clothes you should wear.至于应该穿什么衣服，并没有硬性规定。

英语四级考点归纳:
有关as的常见搭配还有:

※ so as to do sth.意为“为了做某事”。如:
The thief ran off so as not to be caught.为了不被抓住，那名窃贼跑开了。

※ as for意为“至于，关于”。如:
You can stay; as for him, he can get out of my sight.你可以留下来，至于他，他可以从我眼前消失了。

※ as if/though意为“似乎，仿佛，好像”。如:
It sounds as if he's been really ill.听起来他好像真的病了。