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.

It is well-known that crack cocaine is a powerful             drug and users become           to it much more easily if they smoke it.

addicted; addict

addictive; addict

addicted; addictive

addictive; addicted

考查形容词辨析。众所周知可卡因是一种强大的令人上瘾的毒品，如果使用者吸了它更容易上瘾得多。addicted上瘾的，着迷的；addict"shi使沉迷；使上瘾”是动词；addictive “使成瘾的，令人沉迷的”。第一空表示“令人上瘾的”用addictive，故排除A，C项；become addicted to “对....上瘾”，第二空填addicted。故选D项。

I would really appreciate       if you can make time in your schedules to attend my lecture today.

that

it

this

one

考查形式宾语。句意：如果你今天能从日程安排中抽出时间来听我的讲座的话，我将不胜感激。I would appreciate it if/when...如果/当...时，我将非常感激。it 做形式宾语。故选B项。

It’s his brother ______ never been to Australia. You’d better take him with you.

that is

who is

that have 　

 who has

句意：就是他的弟弟从没去过澳大利亚。你最好带他和你去。根据句意及题干分析此题是考查强调句型，因为强调的是his brother，是人，所以用who引导是现在完成时态，故选D。

When            to someone,I usually say, "Pleased to meet you."

introduce

introduced

introducing

am introduced

考查过去分词和省略。句意：当我被介绍给别人时，我通常会说：“很高兴认识你”。根据句子结构可知，本句是when引导的时间状语从句，原句when I am introduced to someone,这里当从句主语与主句主语一致时，并且从句的谓语动词有be这时从句的主语与be同时省略，所以空格处introduced。故选B项。

--- I'm afraid I can't complete the marathon next week.

---              ! You have been practicing a lot.

No problem

Go ahead

Cheer up

Good luck

考查交际用语。句意：---恐怕我下周不能完成马拉松比赛。---振作起来！你一直一直在不断练习。A.No problem没问题；B. Go  ahead请干吧；请便吧；C.Cheer up高兴起来；振作起来；D. Good luck祝您好运。由下文可知说话人担心，完不成马拉松比赛，由“你一直不断练习”可推断表示鼓励“振作起来”。故选C项。

Only after my friend came ______.

did the computer repair

he repaired the computer

was the computer repaired

the computer was repaired

句意：直到我的朋友来了之后电脑才被修理。放于句首的only修饰时间状语从句after my friend came，主句应进行部分倒装，将助动词was提到主语前面，故选C项。