—Look, John‘s fallen asleep at work!—Oh, he must have ________ late last night.
_____ hard she tries, she can hardly avoid making mistakes in her homework.
When you read the book, you' d better make a mark _____ you have any questions.
Helen listened carefully _____ she might discover exactly what she needed.
You may arrive in Beijing early _____ you mind taking the night train.
Bring it nearer _____ I may see it better.