综合测试题二、单项选择21. Oranges are usually sold by _ weight and eggs are sometimes sold by _ dozen. A. the; theB. /; aC. /; theD. the; a22. Though punctual herself, the professor was quite used _ late for her lecture. A. to have studentsB. for students beingC. for students to be D. to students being23. When people move to another country, they often try _ the customs of their native land. A. to keep onB. to keep off
