Digital learning systems （主语）//（时间状语）now //（谓语动词）charge //（宾语）students //（原因状语）for access codes needed to complete coursework

数字学习系统现在向学生收取完成课程所需的访问代码的费用。

for access codes needed to complete coursework.（介词+名词+后置定语/过去分词充当）（介词for+名词access codes=构成介词短语）

=for access codes which are needed to complete coursework（介词+名词+定语从句.不定式to complete coursework在定语从句作目的状语。不定式逻辑主语是“access codes或者关系代词which”）（介词for+名词access codes=构成介词短语）

重点结构如下

(1)charge sb for sth 向某人收取某事费用

(2)charge students for access codes 向学生收取存取/访问代码的费用

(3)needed to complete coursework为过去分词作后置定语相当于定语从句“which are needed to complete coursework=需要用来完成课程的”

(4)sth be needed to do sth 需要某物去做某事

(4)charge vt.向…收费;charge sb for+收费原因/理由

The hospitals charge the patients for every aspirin.

医院每一片阿司匹林都要病人掏钱。