It was not until 1920 ___ regular radio broadcasts began.

when

which

that

since

此题考查强调句。句意为：直到1920年，常规的电台才开始。这句话把it is/was和that去掉后，仍是完整的一句话，因此我们可以知道这是一个强调句，而且是对not...until“直到...才”的强调。结构是：it is/was+not until+其他成分。故选:C.

Every evening after dinner, if not ________ from work, I will spend some time walking my dog.

being tired

tiring

tired

to be tired

考查省略句。当状语从句的主语和主句主语一致，且状语从句中有be动词的时候，可以把状语从句的主语和be动词一起省略，本题if后面省略了I am，句意：每天晚上吃完晚饭以后，如果不是很累，我就会花点时间来遛狗。故C正确。

Let's learn to use the problem we are facing         a stepping-stone to future success.

to

for

as

by

考查介词词义辨析。句意：让我们学会把我们所面对的问题作为通向未来成功的手段来利用。A.to朝，对 ；B.for 为了，对于；C.as 作为；D.by通过，凭借。根据句意可知，此处“作为”符合语境。故选C项。

The old rules have to be          because they only applied to the circumstances that existed when they were made a hundred years ago.

developed

established

observed

revised

考查动词的辨析。句意：老的规则需要被修改因为它们只适合一百年制定时的状况。A.develop发展；培养；B.establish建立；C.observe观察；D.revise修改，由because they only applied to 可知它只适用于以前，需要修改。故选D项。

Her father         a writer.

turned

grew

has turned

has become

考查系动词的区别。句意：她的父亲变成了一位作家。Turn，grow，become用作系动词均可表示“变化”，使用时要注意：become主要指一个人暂时性的身心变化或永久性的自然变化，另外还可用于指天气变化和社会的趋势；grow主要表示逐渐变化，强度变化过程；turn后接名词，往往表示意想不到的变化，名词前通常不加冠词。故选D项。

It was along the Mississippi River _________ Mark Twain spent much of his childhood.

how

which

that

where

此处构成It was...that...强调句式，句中强调了介词短语along the Mississippi River。故选C。

Which of the following does not contain the sound [ae]?

grade

glad

bad

land

考查语音。句意：下面哪个不包含这个发音[ae]? grade的发音是[greId]; glad的发音是[glaed]; bad的发音是[baed]; land的发音是[laend]。故选A项。

It was last night ________ I saw the comet.

the time

when

that

which

强调句的结构是：It＋be＋强调部分＋that(who)＋主谓句。强调句的连词只有两个，that和who。当强调的部分是人，且为句子的主语时，才用“who”，其余用that。因此选C。