本题

What you said is irrelevant to the subject.

你说的与本题无关。

Because the main subject involves the strong corrosive acid, has used the glass lamella lining especially.

由于本题涉及强腐蚀性的酸，特采用了玻璃鳞片衬里。

I would like to know if I could ask for a sick leave of absence from classes for two days.

从本题所给的信息可以判断出，这里要求完成的是一封请假信。

Leaver was stricken with cancer 50 years ago.

解析：21。意思是：短文倒数第二段最后一句说" Leaver 50年前战胜了癌症，这是第一次，也是唯一的一次"，可见本题是正确的。

A left-luggage office is a place where bags___ be left for a short time, especially at a railway station.

答案为 B。本题考查对于情态动词在特定语境中运用的掌握情况。

What is the main subject of the conversation?

本题考查的是会话的主题。

In 1858 he sent me a memoir on this subject.

他于1858年，曾寄给我关于本题的一篇论文。

Nonimmigrant visas for journalists are among the most widely known.

本题为细节题，侧重点是综合信息能力。

One hundred and eleven cases of acute cerebral infarction were divided into 8 groups based on treatment methods and the sequence of attack.

本题选择 111例急性脑梗塞患者，根据治疗方法和发病时间顺序将其分为 8组。

W: Not now, it ' s out of season and they are all very cheap.

本题考核获取重要的事实信息的能力。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。