-Where have you been recently? -I __ ___ in Hangzhou on business for a week last month.
The news shocked the public, ________to great concern about students’ safety at school.
.Everything comes with________ price; there is no such________ thing as a free lunch in the world.
Teachers recommend parents________ their children under 12 to ride bicycles to school for safety.
For many years, people________ electric cars. However, making them has been more difficult than predicted.
In April, thousands of holidaymakers remained________ abroad due to the volcanic ash cloud.