what do you usually do at weekends?at weekends为什么不用介词on

what do you usually do after What do you usually do on weekends? what.do.you.usually.do.in.spring? what do you usually do for fun what do you usually do onweekends中文 what do you usually do after class? what do you usually do in summer? What do you usually do on Saturdays? what do you usually do in fall? What do you always/usually/sometimes/never do?What do you always/usually/sometimes/never do? what time do you usually get up What time do you usually to school? what do you usually have for breakfast what ___do you usually do on sunday? What do you usually have for lunch? What websites do you usually visit?Why? What ___does you usually do ___in Sunday? What do you usually have for Thanksgiving?