To improve their oral English, everyone in the class is supposed to ________ actively in these discussions.
After a knock at the door, the child heard his mother’s voice ______ him.
Pop music is such an important part of society ______ it has even influenced our language.
With the help of high technology, more and more new substances ______ in the past years.
--- Guess what! I have got A for my term paper. --- Great! You ______ read widely and put a lot of work into it.
--- Did you tidy your room? --- No, I was going to tidy my room but I ______ visitors.