20.The river, ________ banks are covered with trees, is beautiful and it attracts many water birds.
— Jake told me he was in the museum just now. — He is actually at home.________, he’s upstairs doing his homework.
Only in this way _______ to make improvement in the operating system.
— We need an immediate reply. — I see. I will send the paper to you ________.
The past 30 years__________ the great changes that have taken place in my hometown.
There are more than three________ students in our school. Look, _________ students are having a gathering on the square.