He often helps the students _______ he thinks are not quick at their studies.
7. This year is very special, _______Chinese New Year' s Day falls on Valentine' s Day.
6. How can you call it home? It' s__________a house.
5. When _______about one of the biggest concerns today, many people mention the sharp rise in prices.
4. People begin to know that most environmental problems exist because necessary measures for preventing them _______taken in the past.
3. To write a novel is not as easy as you imagine. It will take a lot of time and_____.