All students have free access to the library.

A. passageway  （尤指两面有墙的）通道，走廊,过道

B. entrance 入口，进口；进入；进入方法，进入方式；入场权 

C. permission  n. 允许；批准，正式认可，认可

D. access 进入（权）；通道;入径

D为正确答案

All students have free access to the library.

所有学生都可自由进入图书馆。

(1)access 强调“进入某个地方的权利，查阅某个内容权利和机会，或者与某人见面机会”（give/gain/offer access to sth)

The facilities have been adapted to give access to wheelchair users. 

这些设施已经改造过以方便轮椅使用者进入。

Scientists have only recently been able to gain access to the area.

科学家直到最近才得以进入该地区。

The Mortimer Hotel offers easy access to central London. 

从莫蒂默旅馆去往伦敦市中心交通近便。

a Code of Practice that would give patients right of access to their medical records. 允许病人查看自己病历的职业准则

whether one has access to a dish and the other accoutrements needed to watch satellite TV. 

是否能使用碟型卫星天线以及其他观看卫星电视所需要的装备

He was not allowed access to a lawyer. 他未被获准见律师。

My ex-wife deliberately sabotages my access to the children. 

我的前妻蓄意阻挠我见孩子

(2)entrance： 含义广泛，作"进入"解时，可用于许多场合；作"入口"解时，指有门或栏的入口处。(gain entrance to; make one's entrance into )

Hewitt had gained entrance to the Hall by pretending to be a heating engineer. 

休伊特装扮成供热工程师从而进入大厅。

He made his entrance into the parade ring. 他走向赛马准备区。

entrance, entry,access, admittance, admission这些名词含有“入口，进入”之意。区别如下

(1)entrance： 含义广泛，作"进入"解时，可用于许多场合；作"入口"解时，指有门或栏的入口处。

Hewitt had gained entrance to the Hall by pretending to be a heating engineer. 

休伊特装扮成供热工程师从而进入大厅。

He made his entrance into the parade ring. 他走向赛马准备区。

(2)access 强调“进入某个地方的权利，查阅某个内容权利和机会，或者与某人见面机会”

(3)entry： 强调正式地、礼仪地进入。用作"入口"解时，多指房门、院门、门廊等。

(4)admittance： 指许可进入某地或某建筑物。

(5)admission： 指被允许进入某公共场所或建筑物的权利，也指进入某一组织。