30. Even if you are an experienced teacher, you sometimes ____ make some mistakes.
China is still an agricultural country and peasants ________ most of the population.
The foreigners paid a visit to the theme park, ________ with satisfaction.
You’re sure to make rapid progress if your plan for study ________ ahead of time.
--It’s reported that the new underground line has been completed. --Yes, but it hasn’t been made clear ________ it’s to be opened to traffic on time as planned.
________ a diary every day, and you’ll improve your writing.