The writer cries partly because _____ .

• A、she is disappointed that they have to move to California

• B、she is afraid her son cannot find a job after graduation

• C、she misses the days when she could often see her son

• D、she feels sad that her son has achieved little at college

54.________.

He left for New York_________I could say goodbye to him.

• A、as

• B、until

• C、since

• D、before