They usually do some office work weekdays.A.in \x05B.on \x05C.at \x05D.both B and C

They usually do some office work weekdays.A.in \x05B.on \x05C.at \x05D.both B and C
They usually do some office work weekdays.
A.in \x05B.on \x05C.at \x05D.both B and C

They usually do some office work weekdays.A.in \x05B.on \x05C.at \x05D.both B and C
选D
解析：on weekends 和at weekends都是在周末的意思,他们唯一的区别只是一个是美国说法,一个是英国说法,意思都一样,都对
翻译：他们经常在周末办公

exercises excercises exercises exercise

B
The library is open on weekdays only.
这个图书馆星期一至星期六都开放。
I don't stay out late on weekdays.
工作日的时候我不在外面呆得很晚。

B on weekdays =at weekday 在工作日