和"无论如何"，都不符合句意。

　　11．The workers, who had been on strike for three days, demanded that their wages ________ by at least 20%.

　　A．have been raised B．were to be raised

　　C．had been raised D．be raised

　　解析：选D　demand作"要求"讲时，其后的宾语从句谓语用虚拟语气"(should)＋动词原形"。

　　12．The ________ man turned a deaf ear to my explanation though he knew what I said was reasonable.

　　A．worthy B．merciful

　　C．reliable D．stubborn

　　解析：选D　由语境"尽管那个人知道我说的有道理，但就是充耳不闻"可知，他很固执(stubborn)。worthy"令人敬重的"；merciful"仁慈的，慈悲的"；reliable"可信赖的，可依靠的"。

　　13．-Amy and Sarah have ended their friendship.

　　-Why did they ________？

　　A．turn up B．break up

　　C．spring up D．swell up

　　解析：选B　根据语境"Amy and Sarah have ended their friendship"可知选break up，意为"破裂"。turn up"出现"；spring up"突然兴起"；swell up"肿胀，膨胀"。

　　14．-You should have stopped Bob going hiking alone in such weather.

　　-Well, I sought ________ him, but in vain.

　　A．persuading B．to persuading

　　C．having persuaded D．to persuade

　　解析：选D　seek常用于seek to do sth.，意为"试图做某事"，故选D项。

　　15．________ news came ________ an unknown disease was spreading in the area.

　　A．Disturbing; that B．Disturbed; which

　　C．Disturbing; which D．Disturbed; what

解析：选A　句意：一则关于一种未知疾病在该地区呈蔓延之势的令人不安的消息传来了。news为中心词，说明其特征，用现在分词作形容词；news为先行词，that引导同位语从句。