In the distant past, friend relied on each other for their survival. They hunted together and defended each other against【1】_________(danger) animals and enemies. In those days, if you didn’t have a friend, you would either starve, be eaten 【2】_________ killed. Nowadays, friendship isn’t 【3】_________(exact) a matter of life and death. However, friendship is still of great importance and not having a friend is something to be【4】_________(concern) about. Most people look upon friends as someone they can depend on when they are going 【5】_________ times of trouble. In such times, friends provide them with emotional support and sometimes financial help. It is in these troubled times【6】_________ they find out who their true friends are. As an old saying 【7】__________(go), in times of prosperity, friends will be plenty; in times of【8】__________(suffer), not one in twenty. And there is another saying【9】_________ says you can hardly make a friend in a year, but you can easily upset one in an hour. So do your best to get along with and be grateful to all those 【10】__________ are willing to side with you even when you are in the wrong as they are true friends and they are not easily come by.
【4】concerned 固定搭配：be concerned about对……牵挂，故填concerned。
【5】through 固定词组：go through经历，故填through。
【8】suffering 表示“面对着痛苦”。in times of doing sth.，故填suffering。
【10】who/that all those作先行词，指人，后面是定语从句，从句缺少主语和引导词，故填who/that。
在英语中，我们常用It is/was… who/that结构来突出强调句子的某一成分(一般是句子中主语，宾语或状语)。在这个句型中，it没有词汇意义，只是引出被强调的成分。如果被强调的成分是表示人的词，用who或that来连接都可以。如果是其它成分，则一律用that来连接。It is my mother who/that cooks every day.是我的妈妈每天做饭；It was yesterday that Tom passed in the maths exam.是昨天汤姆通过了数学考试。
1.被强调成分是主语，who/that之后的谓语动词应该在人称和数上与原句中的主语保持一致。It is I who am right.It is he who is wrong. It is the students who are lovely.
2.即使被强调成分是句子中的时间状语，地点状语，原因状语等，也不能用when，where, because，要用 that.
It was because of the heavy rain that he came late.是因为大雨他迟到了。
3.被强调部分既包括人又包括物，用that不用who。lt was the things and people that they remembered that they were talking about.
4.区分定语从句和强调句型某些定语从句和强调句型形式差不多，容易混淆。如果去掉it is/was ...that句子仍然通顺成立，则为强调句型，不成立不通顺，则为定语从句。
It was three years ago that he went to American for a further study去掉It was that句子为Three years ago he went to America for a further study.句子通顺，意思完整，那么，这就是一个强调句型。