【单选题】
He was ____ in his work and didn’t hear me come in.
【单选题】
If they ___ to do this work, he might do it some other way.
【单选题】
His father began to work ______ he was seven years old.
【单选题】
____ is essential to a successful scientist; he cannot hope to make any progress if he cannot work in a controlled way.
【单选题】
As a result of his hard work, he has gained ______ to the Beijing University.
【单选题】
If they______to do this work,he might do it some other way.
【单选题】
After several years of hard work, he ______ pass the entrance exam.
【单选题】
1. If they ______ to do this work, he might do it some other way.
【单选题】
5. His father began to work ____he was seven years old.
【单选题】
6.Sam was ill yesterday, so he _____ his home work.