单项选择题()the day on, the weather got worse.
A. With B. Since C. Which D. As
单项选择题It is said that a grave of a middle aged man ______ about 2,300 BC was found by some English archaeologists in the year of 2002.
单项选择题The headmaster went to Washington ______ the first time last September.
单项选择题I'm tired out. I ______ all afternoon and I don't seem to have finished anything.
单项选择题一般而言,中学英语单元教材可以分为三大系统,它们主次分明,______是源,作业系统和图表系统是流,三者相辅相成。