In China, people walk_____ the street. [ ]

Judy,you look so tired.—Yes, I didn’t go to bed ____ 12 o’clock last night. [ ]

Kate enjoys _______ in this river in summer.

Where is your mother?— She _______ to Sichuan on business. She has ______ there four times recently.

There __________great changes in our hometown in the past fifteen years.