1 . The sports meeting had to be postponed ________ the following day because of the bad weather.

A．unless

B．when

C．until

D．as

2 . True friendship is like sound health, the value of which is seldom known________ it is.

A．when

B．if

C．until

D．since

3 . He continued working up ________ his death（用适当的词填空）

4 . China is playing a key role in an effort to control drug overdoses. However, it will take long and much effort ________ this problem is completely solved.

A．until

B．after

C．before

D．unless

6 . 请你修改以下的每个句子，每句有1处语言错误，错误涉及一个单词的增加或修改。
增加：在缺词处加一个漏字符号（∧），并在此符号下面写出该加的词。
修改：在错的词下面划一横线，并在横线下面写出修改后的词。
注意：每处错误及其修改仅限一词。
1. My new job meant I had to say goodbye to my classmates, my school or just everything else I love in the world.
2. My father is hardworking but goes to work in the field every day.
3. I have been missing you very much after I went to college a year ago.
4. In the end, we drove to a service station and waited there unless the road was clear.
5. Mom, though I may not often say it, I do love you. Nobody can take your part in my heart.Whenever I am, I will always love you.

7 . Count, but never stop________you find the truth.(用适当的词填空)

8 . It was not widely accepted as a travel concept ________ the late 1980s. During that time, increasing environmental awareness made it desirable. （用适当的词填空）